Issued December 1942 Lif -P
Revised July 1946 fi E-5P
United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine
THE DEPENDENCE OF AGRICULTURE ON THE BEEKEEPING INDUTSTRY-A REVIEW
Prepared by the Division of Bee Culture
The principal role of the honeybee is not in the production of honey and beeswax, as is commonly supposed, but in the pollination of agricultural crops for the production of seed and fruit. Without insects to effect pollination, many species of plants will not set seed or produce fruit no matter how well they are cultivated, fertilized, and protected from diseases and pests.
Although the honeybee is the most important pollinating insect, it is but one of many species of bees necessary for the perpetuation of flowering plants. Various species of flies, beetles, and other insects also visit flowers and to some extent pollinate them'. Whereas nectar and pollen are rarely the principal food of other pollinating insects, these substances supply the entire nourishment of both the young and aclults of honeybees and wild bees.
Wherever a proper balance exists between plant and pollinating insects, both flourish., Agricultural development, however, has seriously interfered with this balance. It has demanded the growing of certain plants in enormous acreages and has unwittingly destroyed native pollinating insects as well as their nesting places. As a result the burden of pollination has been increased to such an extent that wild bees are no longer adequate or dependable, particularly where agriculture is highly developed. In many places the depletion of wild pollinators is so acute that honeybees have to be brought in especially for pollination, and so in practically all agricultural areas honeybees- are now the most numerous of the flower-visiting insects. It is essential, nevertheless, to conserve our native pollinating insects, since some species of native bees are more efficient, bee for bee, than honeybees and will work under more adverse conditions. As yet, however, no agency, Federal, State or private, has assumed the responsibility for conserving wild pollinating insects.
The-reduction in wild beneficial insects and the increase in acreage of crops requiring insect pollination have been gradual. While these changes-were occurring, commercial beekeeping had its inception and fortunately so, since the presence of honeybees in some areas has helped to mnake
ii ~ nrtageOf wild pollinators.~ Consequently, plant growers and
generally have not been greatly concerned about pollination
~It ecause some beekeeper has relieved them of this worry by keeping
xistr~es within flight range of their crops.
The service rendered to agriculture by the beekeeper in furnishing
i-.public with pollinating insects has commonly been overlooked, In
; many cases his only reward has been his honey crop, which, until war y-~~,he oft en had to dispose of at depressed prices. In addition, his' b~swere frequently killed through the indiscriminate use of insecticides 1b7 the very man he was benefiting. Under such circumstances, since the
beeeepr interest was not safeguarded by sufficiently high honey prices,
,-ertals, or a subsidy of any kind, the keeping of bees has declined in
communities, and this in turn has meant decreased yields for the griwer of insect-pollinated crops.
Tfhe fertilization of flowers is so imperative that beekeeving tlust
iecred on to maintain a profitable agriculture. Owing to conditionss br" Uught about by the recent war, of which increased acreage of inisect:c(1I1.ated seed crops is but one, safeguarding the beekeeping industry ha become doubly urgent. Beekeeping can be mastered only through years of experience. It cannot be learned as a trade is learned, and there is' no floating population of persons seeking employment in beekeeping. The fact that bees have a propensity for stinging discourages many people from keeping them, and only certain individuals possess the proper temperament to be beekeepers. For these reasons every experienced beekeeper should be encouraged to continue with his bees. It may even become necessary to subsidize the keeping of bees, since there is no practical substitute for honeybees in the transfer of pollen from flower to flower and from plant to plant.
In the following pages literature is cited in support of the premise
(1) that wild pollinating insects are deficient in number adequately to pollinate our agricultural crops, and (2) that at least 50 agricultural crops depend upon honeybees for pollination or yield more abundantly when bees are plentiful. yl/ The specific fruit and seed crops mentioned in these references are tabulated below:
Fruit Crops Seed Crops
Almond Alfalfa Kohlrabi
Apple Asparagus Muskmelon
Apricot Broccoli Onioan
Avocado Brussels sprouts Parsnip
Blackberry Buckwheat Pr --. -er
Blueberry and huckleberry Cabbage PtLiri'ld n
Cherry Carrot Radish~
Cranberry Cauliflower Rap-e
Cucumber Celery Rutabaga~
Dewberry Clovers (alsike, crimson, Squash
Goos eberry red, strawberry, white, Sunflower
Grape and Ladino white) Sweetclover
Mango Collards Trefoil
Muskmelon Cotton Turnip
Peach 8.nd nectarine Cucumber Vetches
Pear Flax Watermelon
Persimmon, native Kale
Plum and prune
POLLINATION RNTJTRIRENTS OF PLANTS 2
Fletcher, S. W.
1941. Pollination. Standard cyclopedia of horticulture, by
L. H. Bailey. v. 3, pp. 2734-2737. New York
p. 2734: ...it is well known that while the flowers of many
plants may be readily fertilized by their own pollen, the offspring
are stronger when pollen from another plant or another variety has had access to the flower. Sometimes pollen from a foreign variety
SThese quotations are for the most part from plant specialists, with only a few from authorities on apiculture.
a/ The underlining in the referencesdoes not appear in the original citations but has been added for emphasis.
i s absolutely essential to the best fruit-f ormation.* This is particular-ly true of certain varieties of the pear. A poor quality of fruit can be prevented only by growing together different varieties. Again,
although a plant may readily pollinate itself, yet the pollen from
another plant or variety may be prepotent over its own. This is to sayi the plant be pollinated by its own pollen along with that of
a foreign variety, that of the foreign variety will usually effect
pp. 2734-5: The flowers of insect-pollinated plants, on the
other hand, are usually showy, and have nectar or fragrance, or both.
The pollen is more or less moist or sticky, so that it is not easily
blown away... As the insect reaches down for the nectar, which is near
the bottom of the flower, some parts of its body are sure to become
dusted wi 'th pollen... Thus cross-pollination, or the transfer of pollen
from the anthers of one flower to the pistil of another, is accomplished.
[Bees collecting pollen are just as valuable as those gathering nectar. In visiting large flowers they may be more effective, as they go directly to the reproductive organs.)
.The value of crossing to plants was first clearly proved by
Charles Darwin in 1859... From the observations of Kolreuter,. Sprengel,
Knight, and his own exhaustive experiments, Darwin showed that
tinued self-fertilization is likely to result in inferior offspring;
while cross-fertilization,,within certain limits, gives greater vigor
to the offspring. Cross-fertilization between different flowers on
the same plant usually has no appreciable advantage.
p. 2736: In the selection of a pollinizer, several points
must be considered: (1) The two sorts must blossoms approximately at
the same time in order that cross-pollination may be possible. The
transfer of pollen from one variety to another is performed mainly by insects. Waugh and Packhouse have shown that practically none of the
pollen of the plum and other stone-fruits is carried by wind,. it being
moist and sticky. The same is true of pears, but apple pollen is
somewhat drier and is wind-blown to a slight extent. The honeibee is the most Important pollen-carrier. Hoover estimates that in Englanfd 80 per cent of the cross-vollinatier, is done by the hive bee, 15 per cent by various wild bees, especially the bumble-bee and 5 per cent
by miscellaneous insects.
[If this was true for England with its large areas devoted to hedgerows, woods, and small-scale farming with many wild areas suitable for the nesting of native bees, then in this country with its large blocks of clean cultivation, dwindling wild areas, its large sheep population and much greater use of arsenicals, the percentage of pollination effected by the honeybee must be even higher.]
pp. 2736-7: Orchard pollination, however, is a broader
problem than the mere detection of varieties that are inclined to be
unfruitful when planted alone, and discovering which are the best
pollinizers for each of them. Experiments in crossing and observations in orchards indcate that nearly all varieties, whether selfsterile or self-fertile, will produce more or better fruit with
foreign pollen than with their own... Yellow Newtown is distinctly
self-fertile in Oregon, yet Lewis noted a decided improvement in the
fruit when Jonathan and Grimee pollen was used upon it. He concluded,
"All varieties of pom-fruits, at least of apples and pears, even
though they may be termed self-fertile, are benefited by having other
varieties planted with them as pollinizers."
1A survey of the literature shows that the last statement is not
confined to fruit but is applicable to many agricultural crops as well. ]
MacDniels, L. H.
1929. Pollination studies in New York State. Amer. Soc. Hort. Sci.
Proc. 1928 1 2i37.
p. 137: The value of having bees and ood pollen varieties
in the orchard is that in some seasons when there are only a few
hours in which bee6 :an fly, satisfactory cross-pollination will be
effected whereas it would not have been accomplished if sources of
good pollen and abundant insects were not close at hand. It is for such minimum conditions for cross-pollination that the grower should
provide. It is also evident that in any region the lack of Dolle2n
carriers in the orchard at blooming time may be the limiting factor
in the set of fruit and that in order to properly understand the
pollination problem a study of the insects of the locality in their
relation to pollination is necessary.
acDaniels, L. H.
1930. Practical aspects of the pollination problem. N. Y. State Hort.
Soc. Proc. 1930: 195-202.
p. 2012 In the foregoing paragraphs much has been said of
the limitations of bees in pollen distribution. It must be borne in mind, however, that for all that, bees are still the most effective pollen carriers there are and that they are the only insect that can
be managed by the or2chardist.
Marshall, R. E., Johnston, Stanley, Hootman, H. D., and Wells, H. o
1929. Pollination of orchard fruits in Michigan. Mich. Agr. I.
Sta. Spec. Bul. 188, 38 pp.
p. 38s The commercial fruit power is almost entirely
ent on the common honey bee for the transfer of pollen from one varieti to another.
There are not enough bees in many orchards to Insure the
setting of a full crop of fruit in years when weather conditions are
not favorable for maximum insect activity at blooming time.
REASONS FOR INAMQUACY OF WILD POLLINATING INSECTS
Authorities universally admit the importance of wild insects in
p-ollinating agricultural crops; yet no State or Federal organization is espDecially concerned with the conservation of beneficial insects. It is a P-arent, therefore, that the destruction of pollinating insects has not been fully recognized as the important cause of decreased seed and fruit production in many crops that are benefited by insect pollination.
Tn considering the part played by wild pollinating insects, it should be borne in mind that most species, with the exception of bumblebees, are solitary insects and reproduce slowly, and since the females have to fly in search of food they are sub jected to such hazards as weather, fastmoving automobiles, natural enemies, etc. Many of the solitary bees are ground-nesting and are corqeq,:-;:tly easily destroyed in areas where agricultural practices demand Lv~i. ;u,',i~ cultivation of the soil.
cr-tain species of flies, beetles, and other insects effect pollina_4~i i are considered of minor importance.
Megee, C. R., and Kelty, R. M.
1932. The influence of bees upon clover and alfalfa seed production.
Mich. Agr. Expt. Sta. Quart. Bul. 14: 271-277.
p. 2711 It is common observation that along with the
decrease in the numbers of bumble bees and other wild bees there has
been a decrease in the production of clover seed.
p. 277: Bumble bees are effective pollinating agents, but,
due to their relative scarcity in the clover and alfalfa seed producing districts of northern Michigan cannot be depended on for
Metcalf, C. L.a, and Flint, W. P.
1928. Destructive and useful insects; their habits and control.
918 pp. New York.
p. 264: Under farrng conditions great changes take place in
the character of the plants grown on the land.* There are no longer
a great number of species, generally intermixed, but a few species occupying the land in nearly pure stands of thousands and hundreds of thousands of acres. This affects the insect population of the
land in two general ways. Many of those which depend on the plants
of one family,. or even on one species of plant, find their food supply
cut off, except in the small uncultivated areas an a ery or
_, disappear from the region, as certain species of' the billbup2s
in drained bottom lands.
Vansell, 0y. H.
1942. Factors affecting the usefulness of honeybees in poll inati on.
U. S. Dept. Agr.' Cir. 650, 31 PP.
p. 2: The orchards were located on top of a ridge, which was
flanked on both sides by uncultivated lands, including both timb-er
and manzanita-ceanothus brush.'
PP. 5-6: In the Camino district honeybees were the most
common visitors to the blossoms, blowflies were next,. and other injsects were scarce. As a rule honeybees visit the blossoms of only one plant species on each field trip, while most other insects frequently shift from one species to another. For this reason no other
insect compares favorably with the honeybee in pollen-distributing
activity. Only honeybees and wild bees collected pollen for removal
to their nests. Ants were surprisingly common in the orchard blossoms, feeding on nectar at temperatures well below that at which flying insects cease activity. Ants were observed-working in early
morning, late evening, and during cold rainy periods, but probably
thiey do not often move from tree to tree. Pollen seemed to offer no special attraction to them, but nectar and possibly sap did, because
frequently these ants were engaged in taking nectar and in biting into tender twigs and the tiny fruit before the petals had fall Ien
Bumblebees worked in the orchards during periods far too
cold for the honeybee. Andrenids and other small bees were varv sensitive to wind movement; they hung to leeward, and as a breeze increased to a gentle wind they disappeared. Honeybees were only
slightly affected by a breeze of sufficient velocity to stop the
andrenids. Wild bees were more in evidence near uncultivated lands.
Blowflies were extremely active on pear blossoms, particularly for several hours before a rain. They also appeared on the sunny sides of tree trunks and limbs, and fed freely, upon the fluid oozing from
blight infections, where no honeybees were found. Syrphid flies
evidently fed more or less on the pollen, but the chief interest of
flies in general was in nectar.
..Note the abundance of the honeybee as compared with ~
A .... uomparison of insect visitors observed on apple, cherry,
pear, and plum blossoms at Camino, Calif., during the
seasons of 1932 and 1933
Insects : Number : Percent of
: of insects : total visitors
a e ees. ...........: 10,774 : 82.3
Blwflies ........... .: 926 : 7.1
Small wild bees......: 759 : 5.8
Sypuid flies....... 200 : 1.5
ombyliid flies......: : 1.3
eaf-cutter bees.....: 33 : .2
others. ........... : 230 : 1.8
Tot : 13 086 : 100.0
Increased Areas under Cultivation
ulti vtion of the land destroys the nests of beneficial insects
and discourages rehabitation. The 1940 census reports a decrease in farm
wood lots nestingg sites) of over 53 million acres since 1910.
1933. Apple pollination studies in the Annapolis Valley, N. S., Canada,
1928-1932. Canada Dept. Agr. Bul. 162, 198 pp.
p 92 Observations were made by Hooper (1929 and 1931) over
eveal years on the numbers of various insects visiting apple blossoms,
and the numbers added up. The district contained many cherry, apple and other fruit plantations and numbers of hive bees were kept. The
land not in orchard was either ploughed land or sheep pasture, not very stable for pollinating insects. The counts on apple were as
Hive bees ........ 374 Beetles ......... 104
Bubble bees ...... 37 Ants ..*........ 51
uiaicti, etc .... 21 Earwigs ......... 3
Flies ............ 23 Thrips .......... 2
P 93: Bumble bees are a variable quantity. They are numerou.
in the region of the North Mountain, and especially in certain seasons,
as in 1930, were a decided factor in pollination of an orchard at
Blomidon, but in 1931 were much less numerous. In 1932 there was an
apparent increase at some points, but, taking the area as a whole, they
cannot be considered an important factor in apple pollination. There is considerable testimony to the effect that the bumble bee population
has declined in recent years. Formerly, it is said that they were common in more or less damp meadows where hand mowing had to be resorted to, but are now much less frequently found. especially in the
Valley proper. Whether this is actually the case, and whether, if
true, it is due to limitation of breeding places, poisoning, or some
other factor, cannot now be determined.
p. 961 Without pursuing this subject further, it may be
pointed out that roadside bank, pastures and dykes do not represent exactly wild conditions, but are the product of human activity. However, neither are such locations intensively cultivated. Cultivated
land and certain soil types, such as light sand or gravel, are not
suited to nesting, which is one reason that the solitary bees are More
numerous in such places as Long Island and along the Morth Mountain,
than they are at Iany points situated in the middle of the Valley.
p. 108: In 1932 the number was less, corresponding to an apparent decrease in the solitary bee fauna from all stations. This observation may be correlated with a heavy mortality occurring among
the solitary bees in the summer of 1931, apparently due to drowning in
the nests following wet weather.
],926. Relation of the honeybee to fruit pollination in New Jersey.
N. J. Agr. Expt. Sta. Bul. 434, 32 pp.
pp. 10-12: The difference in the number of insects present
in the cultivated Triangle plot ... Practically surrounded by tilled land and in the cultivated Starr planting situated beside overgrown
land is quite marked.
Family Triangle Starr
Chironomidae--midges ............... 27 121
Bom idae--bumblebees .............. 4 31
Syrphidae--syrphus flies ........... 25 67
Scarabaeidae-beeties ..........o... 4
p. 27: It has been generally demonstrated that insects, especially honeybees, are factors in the set of fruit.
Another factor is the comparatively high state of cultivation
obtaining in the orcharding districts, which destroys hibernating
places. The conditions do not obtain in the cranberry bogs which are surrounded by overgrown land, as cranberries do not bloom until July,
giving ample time for breeding.
p. 29: The number of species of insects acting as fruit pollenators in southern New Jersey is small; the number of individuals
other than honeybees is small, the lack of pollenizers being most
serious in apple and pear orchards situated in cultured areas, less serious adjacent to uncultivated land, and not a problem at all on
cranberry bogs, surrounded, as they are, with woodland, and blooming
two months later than apple and pear.
Honeybees and bumblebees are the most important insect pollenizers in southern New Jersey. The ease with which honeybees can be supplied as needed is the deciding factor in making them the most
1927. Pollination, an important factor in successful pear production.
Mich. State Hort. Soc. Ann. Rpt. 1927:0 196-199.
p. 199: Bees or other suitable insects are therefore,
necessary for pollen transfer. While other insects carry pollen to
some extent, the honeybee has no equal in this respect. Unfortunately,
tame bees have been greatly reduced in numbers throughout the State
by foulbrood, a very serious disease of bees, while the wild bees have
been greatly reduced in numbers through the extermination of our forests
and the thoughtless cutting and robbing of bee trees.
Legasse, F. SO
1928. Proper pollination of fruit blossoms. Del.. Univ. Azr. Ext. Bul.
15, 20 pp.
p. 5: Poor sets of fruit have long been associated with
rainy weather during the blossoming season. We have learned that this is due to the fact that honey bees, particularly the domesticated ones,
do not fly extensively during rainy, cool, and windy weather, rather
than to the effect of the rain on the blossoms themselves. This is
another condition over which we have little control. The only possible
remedby lies in the harboring of greater numbers of certain wild isects, such as the wild honey bee, which fly under weather conditions
that cause the domesticated bee to cling closely to the hive. Howeverthe prevalent system -of clean cultivation and cover crops, furnishes
no nesting place for the wild bees and is not conducive to their multiplication in our orchards.
Murneek, A. E.
1930. Fruit pollination. Mo. Agr. Expt. Sta. Bul. 283, 14 pp.
p.1: Almost all fruit grown in Missouri are pollinated by
insects. Wind is no factor in fruit pollination. When the orchard
is small and there is a great deal of waste land in close proximity,
enough wild bees, bumble bees and other insects may be present in the
spring to be of benefit in pollination. Put in a region where most of
the land is under cultivation, the common honeybee is the only
insect to reply upon. They are the only pollenizer under the
control of man.
Murneek, A. E.
1937. Pollination and fruit setting. Mo. Agr. Expt. Sta. Bul. 379,
P. 13: Of the various kinds of insects that visit flowers
early in the spring, the cormon honeybee is by tar in the majority.
Moreover,. it has been demonstrated in a convincing way that bees
are of great value in pollination of apples,, pears, cherries, plums and many other fruits. This is particularly true in sections where
most of the ground has been put under cultivation with very little
waste ]and left to harbor wild insects.
Phillips, E. F.
1933. Insects collected on apple blossoms in western New York. Jour.
Mgr. Res. 46t 851-862.
p. 861: It seems probable that the scarlt f wild insects
on ap le blossoms is due to a combination of factors incident to the a culture of the fruit districts. The relatively high land values
tend to reduce waste land and wood lots and also tend to eliminate
the wide fence rows which are favored nesting places for some species.
Cultivation reduces nesting and hibernating places, especially of
solitary bees. Clean cultivation of orchards, where practiced, Still
further reduces the opportunities for the propagation of wild bees.
It is possible that the efforts of fruit growers to control injurious insects in some degree serves to destroy individuals of those species which are beneficial. Beekeepers have observed that dusting destroys
many honeybees, and it is probably equally disastrous to solitary bees.
Tysdal, H. M.
1940. Is tripping necessary for seed setting in alfalfa? Amer. Soc.
Agron. Jour. 32: 570-585.
P. 583: The most effective pollinators in this study have
been fegaohile and Noi bees, several species of which have been
observed working on alfalfa. Other conditions being favorable, it
would appear that one of the most effective means of insuring a seed
crop of alfalfa would be a supply of these small, relatively harmless, hard-working insects. It should, therefore, be sound agronomic practice to encourage their presence in an alfalfa seed field. The writer
has talked with alfalfa seed growers who have plowed through a large colony of these bees, which often make their home in the grTound, and
in some instances it has been known that such practices have destroyed
the entire colony- or at least caused it to move.
P. 584: Entomologists who have observed the alfalfa pollinating
insect population in Nebraska for many years unhesitatingly state
that there are fewer colonies of Nomin species and fewer of
Megachile species than formerly. It is possible that cultivation and settlement has disturbed the wild bees and thus reduced their number. Hence, it is suggested that a decrease in the population of these beneficial insects, together with a possible increase in
harmful insects, may be an explanation for the uncertainty in alfalfa seed production in formerly good seed-producing areas.
Wild pollinating insects apparently do not range widely for food, and since they do not store an appreciable amount of food, concentrated plantings of one crop are not favorable for their development.
Brittain, W. H.
1933. Apple pollination studies in the Annapolis Valley, N. S.,
Canada, 1928-1932. Canada Dept. Mgr. Bul. 162, 198 pp.
p. 9: It should be emphasized, however, that a few colonies
of bees placed in an orchard surrounded by large acreages devoid--of bees is of little or no value. In such situations it M be necessary to have a concentration of from 35 to 50 colonies in order to ensure the pollination of the particular orchard in which the bees
areplacd. In districts where beekeeping is general, however, and
neighbouring orchards are similarly supplied, one colony to the
acre or even one colony to four acres may be sufficient. Owing to
the many factors involved more exact figures cannot be given.* It
must suffice to point out that the provision of as many colonies as
practicable is a useful measure of insurance again tunravour5 =0 weather, and a scarcity of wild pollinators- since it is only the
hive bees that can be increased in numbers at will and placed *here
needed in the orchards. Unfortunately, at the present time, there
is no adequate local supply; inexperience in beekeepinr and the
danger of -poisoning prevents many from adopting this practice who
would otherwise do so.
Hootmmn, Dl. H.
1930. The importance of pollination and the honey-bee in fruit yields.
N.Y. State Hort. Soc. Proc. 19301 49-58.
The location and size of the individual orchard are apparently
the factors that determine whether or not bees are needed. Orchards not too large in size with varieties well mixed, located near woods,
swamps or uncultivated land where wild insects can winter over in large numbers, usually set a satisfactory cro -without additional bees. With the conditions that exist in commercial fruit sections
where whole communities are engaed in fruit'gowing and where
orchards have been planted by the square mile the wild insects are-wholly
Inadequate to pollinate effectively the vast expanse of bloom. It is
in these locations especially that commercial fruit growers are largely dependent upon the honeybee-the only insect admirably
adapted for pollinating fruit bloom that can be readily controlled
Kearney, T. H.
1923. Self-fertilization and cross-fertilization in Pima cotton. U. S.
Dept. Agr. Dept. Bul. 1134, 68 pp.
p. 49: Observation in Arizona has shown that the number of
efficient pollinating insects differs greatly in different localities.2/
Bees and otler active pollinators are normally abundant amonq the
cotton flowers at Sacaton throughout the summer, and-the entire
surface of the stigmas is almost invariably well covered with pollen
soon after the corolla has opened. On the other hand, observations
in the Salt River Valley, at distances of 25 to 40 miles from Sacaton, have shown that insect pollination of cotton there is often much less rapid and complete. The probable explanation is that in recent years an extensive and almost continuous acreage has been planted to cotton,
and the insect population is not large enough to insure thorough
pollination of all the flowers.
Thus, on July 18, 1919, in a field situated near Tempe in
heart of the cotton-growing district, no pollen grains were observed upon the extrastaminal portion of the stigmas at 9 a.m. and very few at 10 a.m. Late in the afternoon of July 20, 1920, inspection of the
same field showed the extrastaminal portion of the stigmas to be
free from pollen in most of the flowers, while the remaining bore only
a few insect-transported grains. None of the flowers examined showed
thorough pollination of the whole stigmatic surface. Two other centrally located fields, one at Phoenix and one near Tempe, which were
examined at 5 p.m. on August 5 and at 4 p.m. on August 6, showed similarly deficient pollination. On the other hand, in fields situated on the outskirts of the valley, at Litchfield and at Goodyear, which
were examined at noon on the same days, bees and other pollinators
were abundant, and the stigmas of the cotton flowers were found to be
well covered with pollen.
p. 50: In the mean number of seeds per 100 flowers, a value
which integrates the percentage of bolls matured and the mean number
of seeds per boll, the increase due to artificial pollination amounted
td 32 per cent, indicating that a substantially greater crop both of
seed and of fiber might be expected if bees were abundant in the Salt
River Valley cotton fields during the blossoming period.
/A pronounced difference in the abundance of pollinating insects at
different localities in Arizona was noted by Cook, McLachlan, and Meade. "At the time of our visits to the fields at Yuma and Sacaton there was a notable difference in the activity of the insects at the two places. Several species of large wild bees that were industriously visiting the flowers at Yuma in September were not seen at all at Sacaton."
Luce, W. A., and Morris, 0. M.
1928. Pollination of deciduous fruits. Wash. Agr. Lcpt. Sta. Bul.
223, 22 pp.
p. 21: Observations made at Wenatchee in the spring of
1926 and 1927 developed the fact that there are relatively few insects
visiting the apple blossom in many orchards. These examinations showed that there was a lack of insect activity necessary to perform the crosspollinizing in commercial orchards. In orchards where there were still
plenty of trees of several different varieties the failure of a crop
was apparently due to lack of insect activity at blossom time. Orchards
nearest the foot hills or open country produced the heavi'est-set 2f fruit. The native bees and insects came in abundance from th eokyo hilly ground near these orchards. This condition has been known to
orvi.i aylcldsrcsfrsvrl ifrn yas
Where wild bees and other insects are abundant, a minimum
amount of help is needed from the honey bee, but-in the large closelyz
planted commercial sections. where there are very few wild bees and other insects visiting the blossoms, more honey bees should be p~rc
Rail-Fence Elimination and Heavy Grazing
Rail fences constitute ideal nesting places for many species of
pollinating insects. The replacement of rail by wire fences has destroyed such nesting places, for wire fences permit clean, close cultivation. The increase in the output of wire fences and their relative cheapness has facilitated the use of stock for cleaning up fence rows and out-of-the way patches of land which would otherwise harbor pollinating insects.
It is an axiom in beekeeping that bees starve on sheep ranges. The sheep trample the ground and eat the vegetation into the ground, leaving few flowering plants.
There has been an increase of more than 4 million head of sheep on farms since 1910.
The practice of pasturing sheep in woodlands is detrimental to the propagation of wild pollinating insects.
Sims, I. H., Munns, E. N., and Auten, J. T.
1938. Management of forest soils. U. S. Dlept. Agr. Yearbook (Soils
and Men) 193 -: 737-750.
p. 744: The number of livestock grazing the farm woods in the
Central States is estimated to be five times the actual carrying
capacity and is maintained largely by supplementary feeding of crop
Spencer, D. A., and Potts, C. 1.
1933. Sheep raising in U. S. has changed greatly since pioneer period.
U. S. Dept. Agr. Yearbook 1933: 261.-273.
p. 264: Sheep Are also raised extensively in the grass-producing areas of the Eastern and Central States, particularly in roln andhily ecionls. Since she r fond of a great variety of weeds and underbrush which cattle and horses do not relish, they are useful
in keeping fields and fence ,corners clean and in utilizing forage
not so well adapted to other livestock.
p. 267: Except where flocks are kept to produce purebred stock,
special crops are seldom grown for the sheep, which-are generally
turned onto psture as soon as the grass begins to grow in the s-ortnv
and remain there until the crops have been harvested, when th are
usually given the run of the fields to graze and to clean up the
weds and remain there until snow falls hyaete are
through the winter on hay and some of the unsalable rouirhage, with
little or no grain.
Foet rsan rs ie
Forest, brush, and grass fires destroy all kinds of wild life, includi~ng pollinating insects. The practice of burning fence rows, railroad right-of-ways, pastures, etc., is highly detrimental to wild pollinating insects, most of which nest in or near the ground.
Sims, I. H., Munns, E. N., and Auten, J. T.
1938. Management of forest soils. U. S. Dept.. Agr. Yearbook (Soils
-and Men) 1938t 737-750.
p. 741t Heavy cutting has commonly been followed by fire, and
examples of serious soil deterioration due to this combination of treatments can be found in practically every forest region of the
country. Some 60 million acres of land have been so completely devastated by this combination that they are unlikely to reforest
naturally and must be planted. The total is being swelled currently
by the addition of 850,00 acres each year, three-fourths of which
is land formerly occupied by conifer stands.
When cut-over land is burned the fire accomplishes in minutes
the degree of Uitter removal that would be achieved naturally only
after several years... This sudden removal of the litter and its
living population sets in motion a chain of events leading directly
to deterioration or loss of the soil.
p. 743: Extreme soil temperatures frequently develop during
the great conflagrations and humus in the upper horizons is oxidized
immediately. The mineral soil has much the same appearance as
samples ignited in a furnace. Accumulations of heavy debris b
with such intensity that the soil is sterilized for years.
The Automobile and Paved Roads
Fast-traveling automobiles kill large numbers of pollinating insects. For every slow, awkward female bumblebee killed in the spring there is one less nest of pollinating insects later in the year. Improved, wellkept roads offer little refuge for wild pollinating insects.
1942. Animal mortality on three miles of Yorkshire roads. Jour. Anim.
Ecol. 11: 37-43.
p. 38: As with the Coleoptera, the Hymenoptera, chiefly bees,
have met their deaths either by being crushed by the wheels of the
vehicles, or in the manner indicated above.
p. 40: A busy road passing through a country district has
a big effect on the animal life in its vicinity.
Throughout the year 1938, the total number of animals (insects)
killed on the 3 miles of road under observation was 687... This is
229 per mile; of which 113.3 were Hymenoptera.
pp. 41-42: Altogether, there were 42 different species of
animals killed on the roads. (The Hymenoptera included were as
Bombus terrestris L. A mellifera L.
B. lapidarius L. C olletes succinata L.
B. muscorum L. Andrena armata Gel.
B. agr6rum F. Vespula vulgaris L.
B. ruderatus F. V. iermanica F.
Poisoning from Insecticides
Thousands of colonies of honeybees are killed each year by arsenidal sprays and dusts. Often the losses occur long after the insecticides have been applied, when brood is fed stored poisoned pollen. Under such conditions bees gradually dwindle and die, and often the owner is not aware of the true cause.
At one timepoisoning of honeybees was confined largely to the fruitblossoming period, when bees took poison from open .blossoms, but now the poisoning continues throughout most the summer because many cover sprays are applied to control injurious insects, particularly the codling moth. Sprays and dusts falling on cover crops in orchards kill both honeybees
end nat ,. The dusting of cotton', pc oes a takes
a Leavy ,,L i of bees.
From an:rwledge of the habits of wil c... .
the fact that the queens obtain their food directIy irom fl< they would appear to be even more susceotible to insecticides than honeybees, since the queen's food is not nectar and pollen but royal jelly. rittain made observations on this point, ~ut care to no definite conclusions as to the over-all effect of the use of insectc:ile on Wii oTin atin7 insects. HP did find, however, lethal amount of ar-,- n olen in the nests of wild bees.
VALUE OF THE HONEYBEE 1 PC'LIATN1 G CROPS
On the following pages will be found a few selected references to
the value of the honeybee in pollinating crops, as mentioned in articles
by recognized authorities in horticulture and agronomy.
Dietz, H. F.
1925. Pollination and the honey bee. Ind. Conserv. Comn. Pub. 52,
pp. 19-20: One thing is certain. The honeybee represents
the highest point that has been reached in the insect world as a
flower pollinator. Its own existence in both the larval and
adult stage are dependent on either pollen or nectar. The habits that it possesses of working one kind of flower at a time make it a more effective pollinator than an insect that visits all flowers
And finally the honeybee is the only one of the insect pollinators
that man has under his control or domesticated, so to speak. All the rest are subject to all the vicissitudes of nature, including
unfavorable weather conditions, food shortage, which cannot be
supplied, and the inroads of natural enemies, including Man. Van
through his varied, often thoughtless and multitudinous activities, is the greatest disturber of the natural order of things, and what he does he must pay the price for in one manner or another. However. by studying the ways of nature he often corrects his errors
and when he needs a general flower pollinator he has but to try
Vansell, G. K., and deOnf, E. R.
1925. A survey of beekeeping in California and the honeybee as pollinizer. Calif. Agr. Expt. Sta. Cir. 297, 22 pp.
pp. 17-18: Of all the insects that visit flowers, bees are
the best adapted by the structure of the body to act as carriers of
pollen. The body and legs are covered with heavy, stiff hairs which are branched or featherlike. These catch and hold the pollen grains,
until they are brushed into a "pollen basket" on the hind lea. In
this carrier the load of pollen is transported to the hive.
However., all bees are not of equal value as pollinizers as some
of them do not visit all. types of flowers. The honeybee and the
bumblebee, however, visit almost all flowers with little restriction
except that they evidently confine themselves to a single species
on any one trip.
We have many native species of bees such as bumblebees, carpenter bee, leaf cutters and others, but only in rare instances are
any of these active during the early spring and then only in very
The bumblebee is one of the earliest of the native bees to
feed in the spring, but the entire colony, except the queen., Derishes
during the winter.
In the spring the whole responsibility of rebuilding the
colony devolves upon the queen. She lays and incubates the-eggs,
seven to sixteen in number, feeds the newly hatched larvae and only after the first brood matures can she give her strength entirely to
brood rearing. By fall the colony may have grown to a size of
from one to five hundred individuals. Certain of the mining bees.,
Halictus which nest in certain cliffs, have one or two generations a year. The spring generation consists of hibernating, fertilized
females which give rise to a summer generation. The leaf-cutting bee, Megachile spp., apparently has but one generation a year and
includes but a small- number of individuals. The carpenter-bee,
Ceratina'dupla, has two broods a year which are very restricted in
These examples are typical. of the life history of our common
native species of bees that have from one to five or six brood cycles annually, while the number of individuals range from a score to a few hundred. Comparing this with the honeybee's record of from twelve to
fifteen brood cycles a year, all the descendants of a single Queen,
which may-reach a hundred thousand bees annually or more., we realize
the wonderful reproductive powers of this insect. It should also be
noted that instead of the death of all the workers, the winter's mortality among honey bees is usually veryslight. From five hundred to
sixty thousand may be present in a single c6lony at the close of winter
and two or more brood cycles may be reared in the spring before many
of the fruit trees bloom.
Gould) Ho P*
1939. Why fruit trees fail to bear. U. S. Dept. Agr. Leaflet 172,
pp. 3-4: Self-sterility is very common. It occurs in many
varieties of apples most varieties of pears probably in all varieties
of sweet cherries, in most if not all varieties of the native and
Japanese Plums. and in some varieties of' European or domestic plm and prie. Sour cherries are considered largely self-fertile, although there is some evidence of parial self-sterility. Yost peach varieties are self-fertile; the J. H. Hale and June Elberta (Mikado)
are notable exceptions, as they require cross-po llination. Sterility
in plums, cherries, and perhaps other fruits may somtimes be due to
deformed or imperfect pistils. Some grape varieties must be crosspollinated in order to be fruitful.
There is~every conceivable degree of self-sterility, from one
extreme whore no fruit sets without cross-pollination to that where
it is so slight as not to be a serious factor in fruit production.
The opinion is commonly held that even the varieties considered to be self-fertile in a high degree will set abttr roof fruitif
cross-pollination occurs. With self-sterility prevailing to so large
an extent in common fruit varieties, the relation-of' weather conditions favorable to the greatest activity of honeybees becomes readilv-ampgent, since it is on them that the fruit grower must de]2end vylarg ely for the cross-pollination of his fruits.
When self-sterile varieties are planted and there are no other
trees of different varieties of the same kind prawing near enjougah to
insure the passing of bees from one to the other, it will befound4
that trees blossom but do not set fruit.
When the tree to be cross-pollinated is in bloom secure some
blossoing branches from a tree of another variety of the sa-me kind
of fruit and place them in a pail or other water container in the toD
of the tree. The bees,* visiting the trees, will also visit the blossoms
on the branches and will thereby transfer the pollen as they-revisit
the blossoms on the tree.
Murneek, A. E.
1930. Fruit pollination. Mo. Agr. Expt. Sta. Bul. 283, 12 pp.
p. 1: With proper care bees winter over in large numbers and
are very active in the spring. They are especially well adapted to
carry pollen. Their bodies and legs are covered with hairs to which
the pollen grains adhere in large numbers. Moreover, the honeybe visits only one kind of flower, like the aDple or the -peach-4 at a
time. Thus they are very effective agents in cross-pollination.
p. 9: It has been demonstrated in many orchards in a convincing
way that bees are of great value for the pollination of apples,
sour cherries, and other fruits. If the orchardist does not ,keep~ his own bees and there are none in the neighborhood, then most certainly
it will pay to secure several hives.
Philp, G. IL., and Vanseli, G. HI.
1932. Pollination of deciduous fruits by bees. Calif. Agr Col. Fxt.
Cir. 62, 27 po.
p. 4: The fruit grower has a pollination problem with almonds,
cherries, plm and prne aple pears, and berries. In general,
apricots, peaches, and walnuts set well with their own pollen and
hence present no difficulties from this standpoint.' The J. H. Hale
peach, howeverI is self-unfruitful and must be interplanted with
some other variety. Recent studies indicate that some varieties of walnuts in certain years do not mature the staminate and pistillate
flowers at the same time and therefore, under these conditions, cannot pollinate themselves.
P. 5: Bees are the most important insects for this work. The
grower should therefore have plenty of bees in the orchard during
the blossoming period.
[Honeybees are rented for the pollination of almonds, apples, avocados, cranberries, pears, plums, prunes and cherries, as well as cucumbers and alsike clover.!
Tufts, W. P., and Philp, Guy IL.
1922. Almond pollination. Calif. Agr. Expt. Sta. Bul. 346, 35 pp.
p. 24: Pollenizing agencies, such as the honey bee, are necessary to the set of a good crop of fruit. One colony of honey bees
should be provided for each acre of orchard.
Crane, H. L., and Reed, C. A.
1937. Nut breeding. U. S. Dept. Agr. Yearbook 1937: 827-889.
p. 8721 The pollen of almond and tung trees is carried by
Auchter, E. C.
1924. The importance of proper pollination in fruit yields. N. J. State
Hart. Soc. Proc. 1924: 133-142.
pp. 140-1411 The value of bees in pollination. The carrying of
pollen from one variety to another is accompli 'shed by wind and bees.
It has been found, however, that pollen is carried only very short
distances by wind, but that bees play a very important part in carrying
In crossing into the blossoms to Rzet the nectar, their bodies
become dusted with the pollen. This pollen is then left on the stigmas
of other blossoms when they are visited. In California the investi-
gators are recommending one hive of bees per acre for pollination purposes.
A few years ago, the writer helped to conduct a spDecia. test to prove the value of cross-pollination and bees in a bearing Rome Beauty orchard in 'Nest Virginia. This orchard consisted of aporoxdmately twenty acres and was planted at quite a distance from any other orchards. Although it blossomed well each year, the set was always very light. During the blossoming time f or two years bees were placed under sixteen trees in the center of the orchard and blossoming limbs of other varieties were secured and placed in pails of water, which were hung in the Rome Beauty trees. The bees worked back and forth through these blossoms and an excellent set was secured each year on these sixteen trees. The rest of the orchard, at some distance from the bees, set only a lih rp
A similar test conducted in 1922 in a bearing Stayman Winesap orchard in Maryland where bees were placed in the orchard, together with blossoming branches of the York Imperial variety in pails of water, resulted i fir crop of fruit being set, even though the season was unfavorable for pollination purposes due to some frosts and cold windy weather. In previous years. without bees or the York IM rial blossoms, vy little fruit "set" although there were Plenty of Stayman blossoms and the weather was favorable.
In 1923 with good pollination weather and Grimes blossoms placed about the bee hives, a good set of fruit was obtained in this orchard.
In some special tests at the Experiment Station in 1923, two trees, one a Grimes and one a Stayman WinesaD, 40 feet apart, were inclosed in a large muslin frame 14 feet wide, 14 feet high, and 55 feet long.
A muslin partition was built through the center of the tent (long ways) so that one-half of each tree was on one side of the partition and one-half of each tree was on the other side. Bees were placed in one side of the tent, so that they could fly back and forth between the halves of the Grimes-and Stayman Winesap trees. No bees were placed in the other side of the tent. In the side in which bees were placed, fruit set on the halves of both the Stayman Winesap and Grimes trees. In the other side of the tent without bees, no fruit set on the halves of the same Stayman WinesaI2 tree, although
the Grimes,* being a self-fertile variety, did set some fruit. Apparently in the one-half of the tent, the Grimes pollen was carried by the bees to the Staya WinesaR giing a set, while in the other
half, the Grimes pollen did not reach the Stayman blossoms.
Another test of the value of bees was indicated in some experiments carried on at the College in 1923. Two hundred and fifty
blossoms each of Baldwin, Lawyer, Stayman WinesaD and Kinnaird were emasculated and left unbagged or open to cross-pollination. Apparently, because all of the petals had been removed by emasculation, the bees were not attracted to these blossoms. As a result, not a
blossom on any of the emasculated blooms "set." Other unemasculated
blossoms (with their petals expanded) on the same limbs were apparently visited by the bees so that cross-pollination took place. In
these cases 21.4 per cent of the Lawyer blossoms, 6.4 per cent of the
Kinnaird, 15.8 per cent of the Baldwin, and 5.3 per cent of the
Stayman Winesap "set" fruit.
From the above experiments, it can be seen how important it is
for orchardists to have several hives of bees scattered through their
orchards. The last experiment also suggests that a great many bees might be killed if poisonous sprays are used when the petals of the
blossoms are showing.
MacDaniels, L. H., and Heinicke, A. J.
1929. Pollination and other factors affecting the set of fruit, with
special reference to the apple. N. Y. (Cornell) Agr. Expt.
Sta. ul. 497, 47 pp.
pp. 4-5: The flowers of the apple and of most of our fruit
plants are adapted by their structure to insect pollination. The
showy petals, the odor, and the nectar-secreting glands have the
function of attracting insects which carry the pollen from flower
to flower. The pollen itself is of the sticky tyne that adheres to the hairy coat of insects which visit the blossoms ... rather than of the light dry type that is adapted to wind dissemination.
When it is appreciated that it would take approximately 400 aDDlepollen grains placed side by side to reach from one end of a bee to the other, and that the number carried by a single bee might easily
approximate 100,000, some idea of the possible effectiveness of
insect pollination can be gained.
Overholser, E. L.
1927. Apple pollination studies in California. Calif. Agr. Expt.
Bul. 426, 17 pp.
p. 15: The use of bees as a means of effecting pollination
in an apple orchard greatly increased fhe set of fruit when contrasted with the normal set.
Cross-pollination increased the set of fruit, even with selffruitful varieties like the Yellow Newtown.
Swinson, C. R., Weaver, F. P., Dadisman, A. J., Vernon, J. J., Gould, H. P.,
and tincer, J. B.
1927. Factors infliancing the rield of apples in the Cumberlal
Shenandoah region of Pennsylvaiia, Virpinia, West Virginia.
U. S. Dept. k-h."',ch l. 25 po.
p. 21: A nxiuer of arowers attributed low yields to failure
of fruit to set. It was commonly observed that the low yields of the Winesap and varieties of the Winesap family were ascribed to
this factor. These varieties are largely self-sterile and must be
cross-pollinated by some other variety. Self-sterile varieties
should not be planted in solid blocks or isolated front other orchards.
Where self-sterile varieties have 'been so planted the results may be
improved by top-worcing every fourth or fifth tree in every fourth
or fifth row with some variety that is a good cross-pollinizer. Bees
are essential in aniy orchard and are effective in securing pollination even during cold, wet seasons.
Stout, A. B.
1933. The pollination of avocados. Fla. Agr. Expt. Sta. Bul. 257,
p. 42: It is without; ,obt advisable (1) to interplant
avocados on the basis of thoi:., flower behavior (2) to supply bees
in abundance to effect pollination.
Traub, H. P., Pomeroy, C. S., Robinson, T. R., and Aldrich, W. W.
1941. Avocado production in the United States. U. S. Dept. Agr. Cir.
620, 28 pp.
p. 3: With some varieties, as Fuerte, there is sufficient
overlap of the two sets of flowers to render them self-fertile; with
other varieties, a sufficient percentage of single-cycle flowers
(completing their anthesis tn one opening) are produced to render
self-pollination easy of accomplishment, the only requirement in
each case being the activity of bees or other insects
Keeping bees in or about the orchard is also considered a
'wise provision during the blooming period. Observations indicate
that pollen is carried considerable distances by bees and doubtless
by other flying insects.
!Mrrcw, G. M.
1937. Blackberry and raspberry improvement. U. S. Dept. Agr. Yearbook 1937: 496-533.
p. 498: Normally the wild blackberries of the East are entirely
cr arly self-sterile, and those of the Pacific coast have male
ad female organs on separate plants. All need cross-pollination.
In the clearings and pastures bees and other insects have crossed
the blackberry species for the last 100 to 300 years.
Raspberry, Blackberry, Dewberry (Rubus )
191. The botany of crop plants. Ed. 3, 608 pp. Philadelphia.
p. 340: Pollination. As a rule the anthers and stigmas mature
simultaneously. There is abundant nectar secreted by a fleshy ring
Sthe margin of the receptacle, inside of the stamens. Insects
acilitate pollination. Better yields are secured, in the case of ome dewberries, if they are planted adjacent to another variety so
that cross-fertilization will result.
Blueberry and Huckleberry
rill T. A.
1936 Pollination of the highbush blueberry. Mich. Agr. Expt. Sta.
Tech. Bul. 151, 34 pp.
p. 33: Of much greater importance than self or cross-pollination, though it receives little space in this report, is the need
of insuring some (any) sort of pollination. Mechanical aid is
asolutely necessary to a good set, from self as well as from cross.c..llination.
Bumble-bees and honey bees play a very active part in blueberry
>pps) Co R.
!93O. Blueberry and huckleberry insects. Maine Agr. Expt. Sta. Bul.
356, pp. 107-232.
p. 116: In conclusion, then, the investigations thus far have
~.wn: (1) that various species of insects, especially honey-bees,
2unble-bees and other bees, collect blueberry pollen (2) that such
sects undoubtedly exert a marked influence on blueberry pollina-,on since their exclusion affects yields so strikingly.
.i ~:, F. S.
1921. Proper pollination of fruit blossoms. Del. Univ. Agr. Ext.
Bul. 15, 20 pp.
p. 10: The experimental results obtained in different
sections of the country on the sour cherry with respect to its
self-fertility do not entirely azree. The majority of evidence, however, indicates that most varieties will set comercial crops
thru the use of their own pollen. Shoemaker ... has recently shown that the set of Montmorency is increased under Ohio conditions by the use of early Richmond pollen, but it is doubtful
whether the increased set will compensate for the space occupied by the trees of the inferior pollinating variety. Interplanting
of several, varieties, better cultural practices, and the placement of bees in the sour cherry orchard is recommended for increasing the set of fruit.
Schuster, C. E.
1925. Pollination and growing of the cherry. Oreg. Agr. Expt. Sta.
Bul. 212, 40 pp.
p. 23: With fruit so dependent upon cross-pollination as are
cherries, the agents responsible for this transfer of pollen need to be considered. The number and presence of wild insects can be controlled very little, but the honey-bee can be controlled to a
great extent. It is becoming the practice for cherry growers
either to keep their own bees or to hire stands of bees during the
blooming season. One hive to one or two acres of cherries is
sufficient if the stands of bees are strong.
The sour cherry may be self-sterile, self-fertile, or partly
self-fertile, depending on the variety.
Tufts, W. P.,. and Philp, G. L.
1925. Pollination of the sweet cherry. Calif. Agr. Expt. Sta. TBul.
385,4 28 pp.
p. 26: Pollinizing agencies, such as honey bees, are necessary
to set a good fruit crop.
At least one stand of bees should be provided for each acre
Darrow, G. M ., Franklin, H. J., and Nalde, 0. G.
1924. Establishing cranberry fields. U. S. Dept. Agir. Farmers' Bul.
1400, 37 pp.
pp. 9-10: Results of investigations by the Massachusetts Agricultural Experiment Station indicate that in that State cranberry
blossoms are pollinated by bees. Bumblebees and honey-bees seem to
be the chief agents of pollination. As the former are not always
abundant many growers keep sial] apiaries.
Bees are not common in the cranberry region of Wisconsin,
and experiments and observations by representatives of the w'isconsin
Agricultural Experiment Station indicate that though they help in
pollination they are not necessary in thAt State under normal conditions. The cranberry blossoms there seem to be practically selffertile. After the flower bud opens ... the pistil grows past the
anthers and may be fertilized then or later as the flower is jostled by the wind. Even in Wisconsin bees may be of great value in hastening pollination, thus insuring uniformity in the time of setting and
maturing the fruit. Without insect aid the pollination is apt to extend over a long period and the fruit likelyto mature unevenly.
Beattie, W. R.
1942. Cucumber growing. U. S. Dept. Agr. Farmers' Bul. 1563, 25 pp.
pp. 12-13: Pollination, or the setting of fruit, on cucumber
vines is dependent upon some outside agency such as bees. Two kinds
of flowers are found on every fruiting cucumber plant-the male ones ...
which supply the pollen, and the female ones.., which produce the
cucumbers. They can be readily distinguished, as the female flower is borne on the outer end of the little cucumber. Usually the male flowers appear in great abundance in advance of the female flowers, which leads to the erroneous notion that the cucumbers are failing
to set fruit. Later, the female flowers appear, and fruit is formed.
Cucumbers grown in the field are pollinated by either tame or wild bees from the neighborhood. Under favorable conditions, cucumbers
grown in frames may be pollinated by natural agencies, but the sashcucumber growers of the Norfolk district provide hives of bees near
their frames when the cucumbers are setting, in order to insure
perfect pollination. Without proper pollination the cucumbers are
deformed, or at least a considerable percentage of nubbins are produced. In localities where 'bees are scarce it is advisable for the
growers of cucumbers in fields to keep bees, in order to insure
Hooper, C. H.
1939. Hive bees in relation to commercial fruit production. Southeast.
Agr. Col. Jour. 44: 103-108, illus.
p. 106: There is an opinion that blossomS that have been
pollinated resist frost better than those that have not been pollinated ... In England a Cambridgeshire grower who had a large acreage of gooseberries and had hives of bees placed amongthem. in na Year in
which frost damaged his neighbours' crops, had a good crop which he
attributed to his bees.
Gooseberry and Currant
Robbins, WO WO
1931. The botany of crop plants. Ed. 3, 60P pp. Philadelphia.
P. 307: Pollination.--Gooseberries and currants are crosspollinated for the most part. Insects are the chief agents in
Olmo, H. P.
1943. Pollination of the Almeria grape. Amer. Soc. Hort. Sdi.
Proc. 42: 401-406.
p. 405: Einset (1) stated that no female grape varieties are
grown commercially in this country because natural cross-pollination
is inadequate to obtain good yields. The Almeria ir California is an exception to this rule. This fact brings up the question as to
whether grape breeders should continue to discard all female varieties
without further tests of their qualities. The exDerience with the
Almeria in California suggests that other female varieties, if they
should possess particularly desirable qualities, right be g-rown
commercially with profit if adequate cross-pollination is provided.
Since it has been observed that bees do work on grape flowers, it
apparstht mcre adequate cross-pollination may be provided for by
introducing hives in commercial plantings to suoplement wind
Fletcher, S. W.
1941. Pollination. Standard cyclopedia of horticulture, by L. H.
Bailey. v. 3, pp. 2734-2737. New York
p. 2736: Of one hundred and forty-five varieties of grapes
tested by Beach, thirty-one were self-fertile, forty-one selfsterile, and seventy-three uncertain.
1937. Grape development and improvement. U. S. Dept. Agr. Yearbook
pp. 639-40: The blossoms of Vitis are arranged in a pyramidal,
loosely branched cluster known as a panicle. In the wild state some
vines may bear only ma~le or staminate flowers, while others bear
perfect or hermaphrodite flowers that have both stamens and pistils.
American native species bear male flowers and hermaphrodite flowers on separate vines, while most European vines of Vitis vinifera bear
only hermaphrodite flowers.
The hermaphrodite blossoms range from flowers having reflexed,
very poorly developed stamens ... to perfect flowers with upright
stamens ... Varieties with reflexed stamens usually do not set fruit,
or set only very loose clusters, unless they are cross-pollinated,
either naturally or artificially.
The pollen grains are deposited on the stigma through natural
or artificial means.
193. Muscadine graDes. U. S. Dept. Agr. Farmers' Bul. 17P5, 36 pp.
p. 17: The pollen is carried from the male to the pistillate
flowers almost entirely by insects.
WJhile the honeyee is a less-effective pollinating insect for
muscadine than for fruiits -with sticky pollen, such as apples, it
appears to have sufficient valeto warrant placing stands of bees
in large vineyards during the blossoming season.
1917. The pollination of the mango. U. S. Dept. Agr. Bul. 542, 20 pp.
P. 4: In spite of the close proximity of anther and stigma, the
transfer of pollen from the former to the latter does not seem to be accomplished easily. Both the stamen and the pistil retain an erect
position throughout, and the pollen as it is shed usually falls upon
the base of the ovary or upon the disk rather than upon the stigma.
The normal method of transferring the pollen from the anther to
the stigma must be through the agency of insects.
p. 6: The industry with which the honeybee goes from flower to
flower, systematically working over the surface of the disk with its proboscis to obtain all the nectar present, at the same time turning its body around in a circle and almost of necessity coming in contact with the anther in its circuit of the disk, makes this insect one of
the most effective pollinating agents.
Beattie, W. R.
1926. Muskmelons. U. S. Dept. Agr. Farmers' Bul. 1468, 38 pp.
p. 21: Growers frequently inquire why the early blossoms on
their muskmelons do not set fruit. Muskmelon blossoms are of two
kinds, staminate and pistillate, or male and female. Following the
natural tendency of all vine crops, a large number of male blossoms
appear in advance of the vines to set fruit. At the base of the pistillate or female blossom is located the small embryonic melon
formed before the 'blossom opened, and it is necessary that the pollen
from the male flower be transferred by bees or other insects to the female-flower. Where melons are grown in greenhouses or in closed
frames it is essential that provision be made for the entrance-of
bees in order that the pollen be transferred.
Peach and Nectarine
Cullinan, F. P.
1937. Improvement of stone fruits. T1. S. Dept. Agr. Yearbook 1937:
p. 675: The nectarine was formerly thought to be a different
species from the peach. It is now known that the Dectarine is simply
a smooth-skin peach. The trees differ in no respect from the peach,
and it is impossible to tell a peach tree from a nectarine tree.
p. 695: Most varieties of peaches are self-fruitful. Occasionally failure to produce crops may be due to pollen sterility, which
is exhibited in a few commercial. varieties, such as J. H. Hale,
Halberta, Candoka, Mikado, and Chinese Cling.
Marshall, R. R., Johnston, Stanley, Hootman, H. D., and Wells; H. Mi.
1929. Pollination of orchard fruits in Michigan. Mich. Agr. Expt. Sta.
Spec. Biil 188, 38 pp.
p. 29: A J. H. Hale peach orchard favorably located on the
Friday Bros.* Farm near Coloma and containing a few scattering trees of other varieties had produced but a few fruits since planting in
1917. When it was learned that this variety was self-sterile, South Haven and Elberta trees were planted in the vacancies as pollinizers for the J. H. Hale. In spite of this provision the orchard produced loe than 10 bushels of peaches in 1926. Before the succeeding blossominiz period. 20 colonies of bees were located in the orchard and it
produced the first crop of fruit in 11 years.
Kinman, C. F., and Magness,, J. R.
1940. Pear growing in the Pacific Coast States. U. S. Dept. Agr.
Farmers' Bul. 1739, 38 pp.
p. 24: That cross-pollination is advantageous to setting fruit
of practically all varieties is now generally conceded. Provisions for cross-pollination should be made, notwithstanding the fact that
such varieties as Bartlett,, Anjou, and others may, under favorable
conditions, set fair crops when -planted alone.
One tree is considered sufficient to pollinize eight others
if bees are aovided to carrsthe pollen.
Tufts, W. P., and Philp, G. L.
1923. Pear pollination. Calif. Agr. Expt. Sta. Bul. 373, 36 pp.
P. 35: Pear fruits resulting from cross-pollination do not
appear to exhibit the same tendrency to fall after the June drop
as do those resulting fr, ,eJ. Pollination.
Pollinating agencies such as honey bees are necessary to set
a good crop of fruit.
Fletcher, W. F.
1942. The native persimmon. U. S. Dept. Agr. Farmers' Bul. 685,
pp. 3-4s The trees are generally dioecious; that is, the
pollen-bearing and fruit-producing flowers are borne on separate
trees. The pistillate or fruit-producing flowers are borne singly, whereas the staminate or pollen-bearing flowers are generally produced in threes. The pollen is very light and powdery, and, although
it is generally distributed by bees that frequent the trees in great
numbers during blossoming time, it can also be carried to great
distances by the wind.
Plum and Prune
Hendrickson, A. H.
1918. The common honey bee as an agent in prune pollination. Calif.
Agr. Expt. Sta. Bul. 291, pp. 215-236.
p. 236: The results of'the two seasons' work seem to warrant
the following conclusions: Both the French and Imperial prunes may
be aided in setting fruit by the use of bees in the orchard during the blossoming period, provided the trees are in a normal, healthy
The absence of bees in the orchard may mean a low percentage of
set with both of these varieties.
Mendrickson, A. H.
1922. Further experiments in plum pollination. Calif. Agtr. Expt.
Sta. Bul. 352, pp. 247-266'.
p. 266: The presence of honey bees materially aided in setting
heavy crops on the following combinations of varieties: Formosa and
Wickson; Beauty and Santa Rosa; Diamond and Grand Duke. Observations,
furthermore, showed that many other combinations were also benefited
by these insects.
Hendrickson, A. H.
1919. Plum pollination. Calif. Agr. Expt. Sta. Bul. 310, pp. 1-28.
p. 27: A comparison over a number of years between trees where
there was an abundance of bees flyng and trees where bees were
scarce, emphasized the desirability of having bees in the orchard.
Even self-fertile vrietiese benefited by the presence
of bees as an agency for distributing Lollen.
Kinman, C. F.
1931. Plum and prune growing in the Pacific States. U. S. Dept. Agr.
Faners' Bu!. 1372, 57 pp.
p. 25: The presence of bees i -he plum orchard at blossoming
time has been demonstrated to be almost an ec. nomic necessity....
Poor crops or perhaps failures ma be expected of self-9terile
varieties where no bees are present, and even with self-fertile varieties the presence of bees has caused a decided increase in
Darrow, G. M.
1937. Strawberry improvement. U. S. Dept. Agr. Yearbook 1937: 445-495.
p. 455: Pollen is carried by bees and other insects, but it is
also thrown out of the stamens as the anthers crack open ... or it
is jarred out and blown by the wind and falls on the pistils. A variety having perfect or hermaphrodite flowers can produce fruit when planted by itself, but one with pistillate flowers cannot set
fruit unless perfect-flowered plants are nearby to furnish pollen
through the agency of bees or other insects.
Robbins, W. W.
1931. The botany of crop plants. Ed. 3, 608 pp. Philadelphia.
p. 347: Fertilization and Development of the Fruit.--Strawberries
are protogynous, that is, the pistils of a flower mature before its stamens. Hence cross-fertilization is secured; and this usually by insects. Non-fertilization or incomplete fertilization is usually
indicated by berries with hard, greenish, undeveloped atices, so-called
Tung. See Almond.
Goff, C. C.
1937. Importance of bees in the production of watermelons. Fla. Ent.
From these observations it is quite evident that the size of
the melon crop may be greatly influenced by the bees. Observations
in Florida and elsewhere show that certain days are favorable for
setting melons while a very poor set will occur on other days, due
to weather conditions. If the favorable days are few and the supply
of bees small, the yield may be small.
It is therefore important that a good set be obtained from the
earlier flowers and to insure this an adediuate supply of bees should be present. Thus, in certain areas at least, the earliness and size of yield may be increased by keeping honeybees near the field gming
the flowering season. In large fields, the best results should be
obtained by having a hive near the center of the field.
Tysdall H. MA.
1940. Is tripping necessary for seed setting in alfalfa? Amer. Soc.
Agron. Jour. 32: 570-585.
P. 582: One factor ... is the effect of constant visits of
honey bees to the same flower. When the bees are extremely numerous the same flower may be visited a great many times, and in this way a
higher percentage of flowers are tripped than shown in Table 10.
Actual counts have shown honey bees to trip as much as 12 percent
of the flowers of a given raceme during the course of two or three
days. This would indicate that honey bees in abundance might be
beneficial for seed setting. It has also been observed that certain
honey bees are much more apt to trip alfalfa flowers than-others, thus indicating rather wide differences among individuals in the
same species. Plants also differ in ease of tripping.
Tysdal, H. M., and Westover, H. L.
1937. Alfalfa improvement. UT. S. Dept. Agr. Yearbook 1937: 1122-1153.
p. 1139: The ability of the honey bee (Apis mellifera L.) to
trio alfalfa flowers is not so easily clarified. Piper et al. found
that honey bees tripped only from 0.3 to 4.7 percent of the flowers visited and many visits to the flower were required before tripping
was effected. Dwryer .., of Australia. has found that honey bees
cause a considerable amount of tripping and has suggested the use of
honey bees in cp es in breeding work. Michigan workers have also
found the honey bee to be effective when confined to smai arlls Helmbold ... states that honey bees collect Aollen cause trijving and attributes more tripping to them than to bumblebees.
Robbins, W. W.
1931. The botany of crop plants. Ed. 3, 6CO pp. Philadelphia.
p. 244: Pollination.-Common asparagus is almost entirely
insect-pollinated. The nectaries are small and concealed at the
base of the perianth. Staminate flowers are first to open,
1937. Improvement in the leafy cruciferous vegetables. IT. S. Dept.
Agr. Yearbook 1937- 283-299.
p. 283: According to most botanists, S cauliflower,
broccoli. reen-sprouting broccoli, brussels sprouts, kale, collar5,
and kohlrabi are very closely related, being horticultural forms of
the species Brassica oleracea L.
p. 291: By planting in alternate rows strains that are selfcompatible but cross-fertile, hybrid seed will result through the
action of insects in carrying the pollen from one strain to the other.
Bud pollination of a few flower clusters of each strain results in enough seed to perpetuate the strains for later crops. Bees have
been found to be very effective agents in the cross transfer of
pollen, and by enclosing the individuals or groups of plants under cheesecloth cages the bees may be used in working out the problem
of obtaining desirable crosses between different strains or increasing
the seed of a number of desirable crosses for preliminary commercial
Pearson, 0. H.
1932. Incompatibility in broccoli and the production of seed undercages. Amer. Soc. Hort. Sci. Proc. 29: 468-471.
p. 469t The results given here indicate that the use of sr-11
numbers of bees under cheesecloth cages is a possible method of o ducing small quantities of broccoli seed, if the compatibi]it, ;ation is such that seed can be produced with the pollen avaiJ abhl.
Leighty, C. E.
1919. Buckwheat. U. S. Dept. Agr. Farmers' Bul. 1062, 24 pp.
pp. 21-22: It is not advisable to gry buckwheat for use
by bees alone. Commercial beekeeping in buc heat-growing
sections is advisable, as bees co make use o0 the flowers produced and may in turn be of use in fertilizing the flowers.
Many buckwheat growers, in fact, ql p that'the weight per bushel
of the seed is heavier wher, the eop has'%en worked largely by
White, J. W., Holben, F. J., and .Richer, A. C.
1941. Experiments with buckwheat. Pa. Agri-. Expt. Sta. Bul. 403, 62 pp.
p. 57: Buckwheat plants are a valuable source of nectar, and
since the common varieties are highly self-sterile, bees are of
great value in bringing about cross-pollination.
Pearson, 0. H.
1932. Breeding plants of the cabbage group. Calif. Agr. Expt. Sta.
Bul. 532, 22 op.
pp. 4-5: Insects visit the flower (Brassica oleracea) freely.
Honeybees, although usually plentiful, often fail to be very efficient, because they do not work at temperatures below 60. F.
Bumble-bees are not very plentiful in California, but usually a
few of them are collecting pollen in nearly every field.
p. 7: Cross-pollination which is the rule in Brassica is
usually brought about by insect visitation. Bees are the active
Robbins, W. W.
1931. The botany of crop plants. Ed. 3, 608 pp. Philadelphia.
p. 510: The flowers are mostly insect-pollinated.
Umbelliferea (Carrot Family)
(Carrot, Parsnip, Celery).
Robbins, W. W.
1931. The botany of crop plants. Ed. 3, 608 pp. Philadelphia.
p. 504: The umbellifers are usually insect-pollinated.
Protandry is common.
Kegee, C. R., and Kelty, R. H.
1932. The influence of bees upon clover and alfalfa seed production.
Mich. Agr. Expt. Sta. Quart. Pul. 14 (4): 271-277.
p. 277: The honeybee was found to be a very effective pollinating agent for June and alsike clovers and for alfalfa and the
presence of large numbers of bees resulted in marked increases in
the seed crops of these legumes.
United States Department of Agricu.lture.
1942. A much larger harvest of hay crop seeds needed in 1942. U. S.
Dept. Agr., Food for Freedom Program, Background Information
Series, No. 7, 5 pp.
p. 3: The placement of one hive of honeybees per acre adjacent to or in an alsike field will materiall increase seed production.
Hollowell, E. A.
1938. Crimson clover. U. S. Dept. Agr. Leaflet 160, 8 pp.
p. 8: Crimson clover is a prolific seed-producing plant and
yields of 5 to 10 bushels per acre are common, depending upon the
thickness of the stand, the amount of growth that is produced, and
the care exercised in harvesting the seed. The florets are selffertile, but bees are effective in tripping and transferring the
pollen, with a consequent increase in the number of seed per head.
The placing of colonies of honeybees adjacent to blooming fields
will effectively increase pollination.
Clover, Ladino White
Hollowell, E. A.
1942. Ladino white clover for the Northeastern States. U. S. Dept.
Agr. Farmers' Bul. 1910, 10 pp.
p. 10: Because cross-pollination is necessary for seed formation, it is advisable to move hives of honeybees adjacent to the
fields before the plants bloom. A minimum of one hive per acre
materially increases seed production.
Hollowell, E. A.
1932. Red-clover seed production in the Intermountain States. U. S.
Dept. Apr. Leaflet 93, 7 pp.
p. 7: The dependence of seed setting on the number and activity
of honeybees and bumblebees is not realized by most farmers who grow red-clover seed. The red-clover flower is practically self-sterile; that is, the pollen of a flower will, not fertilize any other flower
on any head of the same plant. Therefore, before fertilization can
occur, it is necessary that the pollen .be transferred between flowers
on different plants. This cross- ollination is done oriipallby
honeybees, bumblebees, and othe kinds '&fbeep, whose 'esence in large numbers at the time red clever is blowing is essential for large yields of seed. If other nectar and pollen producing plants
more liked by the bees than red clover are available, the honeybees in particular will. work the other plants in preference to the redclover flowers. If only the second growth is saved for seed, .the
time of cutting the first growth may be regulated so that the
second growth will be in full bloom when other flowering plants are scarce and then large numbers of bees are present. There is reason
to believe that in sections where an increase in acreage has been
accompanied by declininayvelds of seed dthe introduction 'o additional
colonies of honeybees would prove profitable. Bumblebee nests should not be destroyed, and every effort shpUld be made to provide desirable
nesting places for queen bumblebees.
Pieters, A. J., and Hollowell, E. A.
1937. Clover improvement. U. S, Dept. Agr. Yegrbook 1937: 1190-1214.
p. 1199: Bees visit the red clover floret for nectar and Pollen
or both, tripping the florets and transferring pollen from plant to
plant, thus constantly maintaining the condition of mixed inheritance in the species. Other insects, such as moths, are constantly seen on red clover heads, but they do not come in contact with the pollen and
therefore do not effect cross-pollination.
There has been considerable controversy as to the extent to
which pollination can be accomplished by honeybees. Discussion has centered upon the fact that the tongue of the honeybee is not long
enough to reach the nectar. The literature on this subject is
voluminous and cannot be reviewed here. More recent investigations
clearly indicate that honeybees visit red clover principally for
pollen and seldom obtain nectar, but regardless of what is obtained,
pollen is transferred and cross-pollination is effected.
United States Department of Agriculture.
1942. A much larger harvest of hay crop seeds needed in 1942. UT. S.
Dept. Agr., Food for Freedom Program, Background Information
Series, No. 7, 5 pp.
p. 3:0 A lack of sufficient pollination insects when red
clover is blooming is one reason for low seed yields. Honybes, one of the principal pollinators of red clover, are the only kind
that can be readily increased and moved. The placement of one
hive of honeybees per acre adjacent to or in a red clover field
when blooming wi'Il in-crease seed production.
Hollowell, E. A.
1939. Strawberry clover. U. S. Dept. Agr. Leaflet 176, 8 pp.
p. 6: The blossoms of strawberry clover are visited by honeybees. Apparently they obtain considerable nectar, which indicates
that this is a good honey plant.
Hollowell) B. A.
1936. White clover. U. S. Dept. Aer. Leaflet 119, 8 pp.
p. 7: White clover is naturally a free-blossoming plant in
all. parts of the United States, but only in a few sections has
seed production developed as a farm enterprise. ... Even when
blossoms are abundant, moist, cloudy weather is unfavorable to
bee activity,and necessary cross-pollination is, therefore, restricted and seed production reduced. The presence of colonies of honeybees in the immediate vicinity of clover-seed producing
fiedsusually insures a maximum of cross-pollination.
Allard, H. A.
1910. Preliminary observations concerning natural crossing in cotton.
Amer. Breeders' Mag. 1: 247-261.
pp. 256-257: Honeybees are among the most frequent visitors
of cotton blossoms, but, at the same time, they are very generally
visitors of the outer involucral nectaries alone. ... Nearly all
4 bee visitors show a marked tendency to pass from plant to plant
4 uD and down the rows rather than across.
p. 258t These casual records are sufficient to show the
enormous number of blossoms a single bee is capable of visiting
a few hours, and the probabilities of intercrossinp a great
Lmr of these all over the field. Almost before day, bees
,re forcing their way into the expanding buds, and an examination of these reveals many whose stigmas have been pollinated
i before the flowers are fully opened. The writer has
erved that in the near vicinity of domestic hives in
northern Georgia the number of honeybee visitors is enormously
p. 261: In cotton fields of northern Georgia the demonstrated
pH_4ortion of crossed blossoms is at least 20 per cent, with strong
probabiities that approximately 40 per cent of the blossom are
crossed. Although crossing may be very detrimental in unselected
cotton, in selected cotton it is probably beneficial.
aney, To H.
1923. Self-fertilization and cross-fertilization in Pima cotton.
U. S. Dept. Agr. Dept. Bul. 1134, 68 pp.
P. 36: There is little doubt that natural cross-pollination
in cotton is effected almost solely by the agency of insects. The
nature of the pollen grains of Gossypium is unfavorable to their
transportation by currents of air.
p. 37: Various Hymenoptera are the most efficient carriers
of cotton pollen at Sacaton, Ariz., as is probably the case wherever
cotton is grown. The honeybee and the wild bees (Yelissodes spp.)
are the most important cotton pollinators in this locality.
The honeybee (Apis mellifica L.) is very assiduous in its
visits to cotton flowers, although sometimes preferring the extrafloral nectaries to- those with the flower. Nevertheless, this
insect probably holds first rank at Sacaton, Ariz., as a conveyor of cotton pollen, especially among Pima flowers. As was noted on
a preceding page, honeybees entering and emerging from the flowers
when the petals are just beginning to unfold almost invariably come
in contact with the reproductive organs.
eade, R. M.
1918. Bee keeping may increase the cotton crop. Jour. Hered. 9: 282285.
p. 285: No effort was made to exclude insects, and the weatherconditions during the course of the investigation were not unfavorable
to their activities. It is evident from the increased yield of bolls secured in the long-pistiled Durango variety through artificial pollination that the presence of additional pollinating insects would aid
in reducing the high percentage of shedding. The value of honey
bees in this connection is recognized in some localities, and it would seem that growers of long stapled varieties might find beekeeping a distinct advantage to the cotton crop.
Cruciferous Root Vegetables
Poole, C. F.
1937. Improving the root vegetables. U. S. Dept. Agr. Yearbook 1937:
p. 310: The cruciferous root vegetables-turnips, rutabagas,
and radishes-have relatively large flowers, which are insect-pollinated.
Jones, H. A.
1937. Onion improvement. U. S. Dept. Agr. Yearbook 1937: 233-250.
p. 239: Most of the pollen is shed between 9 a.m. and 5 p.m.
Pollination is effected mainly by insects that go from flower to
flower and visit the nectaries at the base of the three inner
stamens. Interpollination among flowers of the same umbel is no
doubt of frequent occurrence, as the same insect has been observed
to visit many flowers on an umbel before leaving. In the onion,
however, cross-pollination is the rule.
Odland, M. L., and Porter, A. N.
1941. A study of natural crossing in peppers (Capsicum frutescens).
Amer. Soc. Hort. Sci. Proc. 38: 585-588, tables.
p. 588: The pepper flower is rather inconspicuous and nonfragrant, a fact that would suggest pollination not very likely.
Erwin ... found that the flowers produced nectar and that insects
did at times visit them. The writers are of the opinion that honey
bees are largely responsible for the ck-oss pollination that takes
p This insect has been found working on the pepper plant
rather often. The presence of the bee is rather spasmodic, however, as they are found only on certain warm bright days. The presence of
bees in the vicinity may have a bearing on the amount of cross pollination.
Gutin, A. V. Flax
1945. Cross pollination of fibre flax. Bee World. 26:30-31.
p. 30: Among all insects which pollinate flax flowers the
honeybee occupies a significant place .... The honeybee constitutes
93.8 percent of all such insects.
P. 31: Cross-pollination of flax by bees increased the yield, as measured by quantity of grain, 28-57 percent; as
measured by weight of seed, 31-01 percent and raised the absolute weight of 1000 grains from 5.0372 to 5.1329 gm. Consequently,
the development of seeds with self-pollination proved to be somewhat depressed. Usually with a smaller quantity of seed and fruit
they grow.larger in size; in the given case the reverse was observedthe resultant yield with cross-pollination was higher in respect
of both-quantity and quality.
On the open plot where the number of visits was only 67.8 percent of the number of flowers, the increase of the yield of flax proved to be less significant; the number of grains from 500 bolls rose from 2688 to 3050, that is 13.47 percent; their weight rose from 13-5934 to 15.887P gm. or 1.6.88 percent; the
weight of-1000 grains rose from 5.0576 to 5.2095 gm.
Crane., M. P., and Mather, K.
1943. The natural cross-pollination of crop plants with particular reference to the radish. Ann. Appl. Piol. 30: 361-308.
P. 307: As the radish is self-incompatible each plant must receive pollen from another plant to produce seed. In these experiments the pollen could come from a sister plant of the same variety
or from a plant of a different variety. As shcmrn in Figs. 4-6,
25 hives of bees were maintained close to the experiments. Thus, the bee population was much higher than in most cases where crops are grown commercially for seed, and the number of bees visiting
the plots during the flowering period was extremely large. The
seed crop was heavy throughout the plots, indicating that crosspollination had been effectively carried out.
Kremer,, J. C.
1945. Influence of honey bee habits on radish seed yield. Mich. Agr.
Expt. Sta. Quart. Pul. 27: 413-420. illus.
p. 419: FIgure 4 illustrates a typical example of the effective radius of commercial bee yards located in a radish seed area., where radish seed fields were located without regard or knowledge of their
All the fields located within the circles or the 2-mile radius produced from 400 to 450 pounds of seed per acre, while those on
the border of this radius or beyond averaged 200 to 300 pounds of seed per acre. One field located within the flying radius of two
of these bee yards averaged 600 pounds per acre. No other colonies
of bees were known to exist in this area, thoih possibly there
were some wild swarms present.
Rudnev, V. Z.
1941. IThe effect of pollination by bees on yield of sunflower seeds.)
Soc. Zern. Hoz. No. 2. 134-40. [Abstract in Imp. Pur.
Pastures and Forare Crops, Herbase Abs. 14:55-56, 1944.]
p. 55: Field tests with sunflower plants, which were either
completely or partially covered with gauze to prevent Pollination
by the bees, indicated that percentage of settings was 77.7 to
85.9 in the insect-pollinated and 25.0 to 25.7 in the self-pollinated flowers. Trials in field conditions (when a number of beehives was placed at varying distances from several observation plots 100 m each in a large sunflower plantation) showed that,
with the increase from 500 to 1250 n. of the distance of a beehive
from the plantation, the number of bees visiting each plot dai'y fell from 100 to 61, the weight of ripe seeds dropped from 6,000 to 3,700 grin., and the weight of empty seeds rose from 110 to 200
Peters, A. J., and Hollowell, E. A.
1937. Clover improvement. U. S. Dept. Agr. Yearbook 1937: 1190-1214.
p. 1207: Pollination of sweetclover under natural conditions
is effected principally by honeybees, except insofar as the
species, varieties, or individuals are spontaneously self-fertilized.
United States Department of Agriculture.
1942. A much larger harvest of hay crop seeds need.d in 1942. U. .
Dept. Apr. Food for Freedom Program, Background Informration Sries,
No. 7, 5 pp.
p. 3: ... lack of sufficient pollination lowers seed yields,
Honeybees are the most valuable pollinAtors. A minimum of one hive of honeybees per acre located close to a blossoming field
of sweet clover will increase the quantity of seed set.
McKee, R., and Schoth, H. A.
1941. Birdsfoot trefoil and big trefoil. U. S. Dept. Aqr. Cir. 625,
p. 5: The general conclusion of investigators who have studied
seed setting in Lotus species is that both birdsfoot trefoil and
big trefoil are practically self-sterile. Silow ... who has more
,I VER111 I TYii l OF FLORIDAIIII iiiii i
42 3 1262 09224 7161
recently given the subject consideration draws the following conclusion:
"Lotus corniculatus is practically self-sterile,
but occasional plants set a few sepis after self-collination. P-lants of L. major Smith (- L. uliginosus Schk.)
are, on the whole, incapable of spontaneous self-pollination, but after artificial self-pollination practically
all plants are self-fertile, some to a very high decree.
Thus these two perennial species are almost entirely dependent unon insect visitors for seed formation."
1942. Bliitenbiologische Studien an der Zottelwicke. Pflanzenbau.
Hungarian (Vicia pannonica) and hairy vetch (V. villosa).
were screened to exclude bees. In the former 38 percent of the
flowers produced seed but only 3.5 percent of the latter. Hairy
vetch was found to be self-fertile but to require bees to transfer
the pollen. The author concluded that seed production in hairy
vetch is almost entirely dependent on the visits of bees to effect
the transfer of pollen. [Abstracted from translation by Carlo Zeimet.]
(Hairy, Hungarian, Russian, Siberian, or Villous -Vetch)
Robbins, W. W.
1931. The botany of crop plants. Ed. 3, 608 pp.
pp. 411-412: There are five to eight pairs of leaflets,
and many (about thirty)violet-blue, rarely white, flowers in one-sided racemes. Cross-fertilization is necessary for the
normal production of seeds. Bees are the chief agents in the
dissemination of pollen.