The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
UNIVERSITY OF FLORIDA
Agricultural Experiment Station
ROOT-KNOT AND "WHITE MOLD"
J. R. WATSON
Fig. io-Horn-worm of tomato (slightly reduced).
The Station Bulletins will be sent free upon application to the Experiment
THE E. O. PAINTER PRINTING CO.,
DE LAND, FLORIDA
BOARD OF CONTROL
P. K. YONGE, Chairman, Pensacola, Fla.
T. B. KING, Arcadia, Fla.
E. L. WARTMANN, Citra, Fla.
F. P. FLEMING, Jr., Jacksonville, Fla.
W. D. FINLAYSON, Old Town, Fla.
FARMERS' INSTITUTE STAFF
P. H. ROLFS, M.S., Superintendent.
A. P. SPENCER, M.S., Assistant in Extension Work.
C. K. MCQUARRIE, Assistant Superintendent Farmers' Institutes.
P. H. ROLFS, M.S., Director.
J. M. SCOTT, B.S., Animal Industrialist and Assistant Director.
B. F. FLOYD, A.M., Plant Physiologist.
J. R. WATSON, A.M., Entomologist.
H. E. STEVENS, M.S., Plant Pathologist.
S. E. COLLISON, M.S., Chemist.
JOHN BELLING, B.Sc., Assistant Botanist, and Editor.
O. F. BURGER, M. S., Assistant Plant Pathologist.
SETH S. WALKER, M.S., Assistant Chemist.
J. H. CARPENTER, B.S., Assistant Chemist*.
JOHN SCINABEL, Assistant Horticulturist.
U. C. LOFTIN, B.S., Laboratory Assistant in Entomology.
F. M. O'BYRNE, A.B., Laboratory Assistant in Plant Physiology.
E. G. SHAW, Secretary.
B. V. GLOVER, Stenographer.
K. H. GRAHAM, Auditor and Bookkeeper.
M. CREWS, Farm Foreman.
*Employed for citrus analytical work. Salary paid by the Florida
Boll-Worm, or Tomato Fruit-Worm ............................... 21
Root-Knot .................... ........ ...................... 24
T h rip s ..................................................... ..... 26
Cutworms ........................................................ 28
H orn W orm s ......................................... ............. 30
W h ite M old .............................. ...................... 3.
A phis, or Plant-L house .............................................. 33
F lea-B eetles ................................................ .... ... 35
M miscellaneous Insects .................................. ............ 36
Blister-B eetles ............... ....................... ..... ..... 36
W hite-lined M morning Sphinx ....... ........................... 3
Army W orms .................... ............................ 36
G rasshoppers ................................................. 37
Suckfly ........................ ...................... ........ 37
Tomato W hitefly ........ .. ..... ................... ..... ... 38
Bugs .......... .. ............... ......................... 38
There are many thousands of species of insects. Some feed on cultivated
crops, and may then multiply with great rapidity. In such cases as the invasion
of the migratory locust (or grasshopper), the devastations caused by insects
bring great financial loss and much actual suffering. In other cases, such as
the attacks of the tomato worm (which also injures other crops, including
cotton), the damage done in any one field or locality is not so great as that
done by the migratory locust at its worst. The total annual damage, however,
done by this caterpillar is probably as great as that ever done by the locust.
To combat successfully the ravages of insect and other crop pests, it is neces-
sary to know much about their life history.
Biting insects (those that feed on portions of plant tissue) are usually
controlled by means of internal poisons; while those insects that suck juice
from the interior of plants cannot, as a rule, be treated successfully in this
way. For them, contact insecticides should be employed.
Thousands of species of insects prey upon other insects. If they prey on
insects that are harmful to cultivated crops, they are extremely beneficial. It
therefore follows that we must know something about an insect before we
engage in its destruction. Tens of thousands of.species of insects feed on
decaying vegetable matter and on uncultivated plants; these need not concern
us from an economic standpoint.
In this bulletin Mr. Watson discusses only those tomato pests that are
likely to prove destructive in the Florida tomato field.
P. H. ROLFS, Director.
TOMATO INSECTS, ETC.
J. R. WATSON
BOLL WORM, OR TOMATO FRUIT WORM
This insect is the most serious pest of the tomato. It is the same
species that is so frequently found in the ears of corn (particularly
sweet corn), which is indeed its favorite food. It is then known as
the "corn-ear worm." It also attacks green peas, beans and other
plants, and is particularly
destructive to cotton, be-
ing then known as the boll
EGGS. These are
whitish, ,oval in shape,
about one-twentieth of an
inch in diameter, and, as
shown in Fig. I are
prominently ribbed. They a b
are found scattered here
and there over the food
plants, to which they are
fastened by a white,
sticky secretion. (Fig. ,'P
S1, b, is a view of the egg
from above; Fig. i, a, Fig. II--(From U. S. Dept. of Agr.)-Boll-
worm, or tomato worm, or corn-ear worm
from one side.) (Heliothis obsoleta). a and b, egg (enlarged);
LARVA.-(Fig. II, C). c, larva; d, earthen pupa-case; e and f, moth
S" (natural size).
From the egg there hatch-
-es out in a few days a small caterpillar quite variable in color. This,
in the spring, may be a delicate pink or, more often, darker; the later
broods especially may be quite black. This larva is marked with
rather narrow longitudinal lines. It eats greedily for about three
weeks, during which period it molts several times. When full grown
it is from I'4 to 2 inches long.
22 FLORIDA AGRICULTURAL EXPERIMENT STATION
PUPA.-When full grown, the larva descends the plant and bur-
rows three or four inches into the earth, forming an earthen cell
about itself, in which it transforms to an oval pupa about three-quar-
ters of an inch long (Fig. II, d). This is at first green, but soon turns
to a delicate light brown. The cell is lined with a loose layer of silk.
Its construction, and the change to a pupa, usually take about three
days. The pupa lies perfectly quiet, for several days in the summer
broods, and all winter in the last fall brood.
ADULT, OR IMAGo.-From this underground cocoon there issues
a moth (Fig. Ir, f and e), which varies from dusky yellow to grayish.
The markings on the wings are also variable. The distance across
its outstretched wings is from 1/2 to 2 inches. Unlike most moths,
it may fly in broad daylight; but the eggs are usually deposited towards
LIFE HISTORY.-There are three or more broods in Florida. As
stated above, the insect usually spends the winter in the pupa stage;
but occasionally an adult moth hibernates. The female of the first
brood, after mating, deposits her eggs on a variety of plants, prefer-
ably on corn; but if corn is not to be had, she will choose tomatoes,
and occasionally other plants, such as' peas, beans, squashes and to-
bacco. On the corn, the larvae first eat the leaves, which they riddle
with holes. When the ears begin to form, the worms mostly abandon
the leaves for these. The silk is first largely consumed, and then the
ear is entered and the soft grain eaten. Three or four worms are
often found in a single ear; although in this case the largest worms
will frequently eat the smaller ones. As the kernels of the corn be-
come hard, they are not so much relished, and then the caterpillars
attack cotton eagerly, eating into the young and tender bolls.
On the tomato, which is troubled mostly in early spring, the
eggs are laid on the leaves. The young larvae feed on the leaves for
a day or so, but soon migrate to the stems, into which they bore.
They are prone to wander, however; and the young tomatoes, as soon
as they are set, are attacked by the caterpillars, which entirely desert
the stems. Here, as on other food plants, they bore into the fruit
and mine out the inside. As the hole by which they enter is often
quite small, their depredations are not very conspicuous. Here again
their restless habits come into play, for, instead of confining them-
selves to one fruit until it is consumed, they will desert the first to
attack a fresh one, which in turn is eaten enough to be spoiled and
then deserted for another. In this manner, a single caterpillar may
spoil two or three tomatoes per day, and thus do much more damage
than would be represented by the amount of food actually consumed.
BULLETIN 112 23
PREVENTION.-Because most of the larval life is spent inside of
the tomato, corn-ear or cotton boll, it is practically useless to try to
control this pest by means of arsenates or other poisons, or by contact
insecticides, except in the early part of the season while the insects
are still exposed and feeding on the leaves. If the larvae are very
common at this time, the vines may be sprayed with Paris green, or,
which is better, with lead arsenate, or the newer insecticide, zinc
arsenite, as there is less danger of burning the foliage with these.
During most of the life history of the tomato worm we must
fall back upon cultural methods for protection. This is usually the
most effective way to fight an insect. The great preference of this
insect for corn suggests one method of fighting it; that is, to use corn,
preferably sweet corn, as a catch crop. Wherever the season will
allow, it is recommended that for every twenty-five rows or so of
tomatoes, there be planted two rows of sweet corn. The date of
planting the corn should be chosen so that it will be in silk at the
time the tomatoes are becoming of sufficient size to be attractive to
worms. The moths will lay most of their eggs upon the corn in
preference to the tomatoes. If the larvae attack the corn in large
numbers when it is only knee-high (at which time they are known
as "bud-worms") they can readily be poisoned by dusting a little
dry lead arsenate or zinc arsenite into the bud. The corn should be
cut and fed to stock before the larvae become full grown and enter
the ground to pupate, or before the corn hardens and is deserted by
the caterpillars. Otherwise, like all catch crops, it will be a source
of danger to the tomatoes, rather than a protection. All wormy fruit
should be picked and removed from the field, and so disposed of as
to destroy the larvae. Hogs, and also chickens, will eat a limited
amount of these wormy tomatoes, especially if they do not have ac-
cess to other green food. Where the acreage of tomatoes is large,
the most practical method of disposing of these wormy fruits is to
bury them. They should be covered with at least a foot of well-
packed soil (or more, if it is very sandy) to ensure that the larvae
or the moths will not be able to make their way to the surface. The
practice of dumping the wormy and cull fruits beside the packing-
house or along the roadway cannot be too severely censured. If a
wormy tomato is thrown down in the field, the caterpillar will soon
attack another tomato; or, if full grown, will enter the ground to
pupate. It would be better not to pick the tomato at all than to
throw it on the ground in the patch. Wormy tomatoes can perhaps
best be sorted out at the packing-house. If these caterpillars are de-
stroyed it will greatly reduce the number in succeeding generations.
24 FLORIDA AGRICULTURAL EXPERIMENT STATION
This has been thoroughly proved by experiments on a large scale.
In one conducted by Director P. H. Rolfs, the wormy tomatoes were
carefully picked up from one field while in a neighboring field they
were neglected. In the former at the close of the season there was
scarcely any increase in the worms and only about 5 per cent. of
the fruit was wormy; while in the latter field, 80 per cent. of the
fruit of the later pickings was ruined. It is not too much to say that
for every worm the grower destroys early in the season he will save
a crate of tomatoes later on. Each moth may lay as many as 500
eggs, and there is a generation every 30 days under the most favor-
able weather conditions.
At the close of the picking season, the vines with infested fruit
should be burned or plowed under as soon as possible. This is very
important, as a means of combating not only this insect, but other
insects and fungus diseases as well. Growers sometimes object to
burning old plants, on the ground that they are destroying so much
fertilizer which would be returned to the soil by the rotting of the
plants. While it is true that some of the nitrogen would be destroyed,
the loss is infinitesimal in comparison with that resulting from the
injuries caused by the insects and fungi if they are allowed to live
Birds, especially the bluejay and mocking-bird, feed large num-
bers of tomato worms to their young. These birds, and also wasps,
should be protected by the grower.
This disease, which is so well described by its name, is caused,
not by an insect, but by a microscopic round-worm or nematode
(Heterodera radicicola), which occurs in the soil, and, getting into
the roots of plants, causes the characteristic swellings. Although
it is a serious enemy of the tomato plant, it is, on the whole, causing
less damage than it did at one time (Fla. Agr. Exp. Sta. Bul. 91, p. 28).
The young migrate through the soil but slowly, only about six feet
per year. They are carried by water or by other means. The most
common means of distribution are the feet of the farmer, or of his
domestic animals, and the transplanting of infested plants.
PREVENTION.-It is almost hopeless to attempt to combat these
pests after they have become established in a field, except by cultural
methods; but a great deal can be done towards preventing infestation.
In the case of tomatoes, the first step is to see to it that the seed-bed
is not infested. Otherwise, the young plants will become hosts, and
when they are transplanted into the field they will carry the minute
worms to all parts of it. Under ordinary conditions, the grower can
find a place, such as newly cleared land, that he is reasonably certain
is free from the disease; but he can be absolutely safe by adopting
one of the following methods (taken from Bul. 217, U. S. Dept. of
Agr., Bur. of Plant Industry) :
(1) Punch eight or nine holes per square yard into the seed-bed
to the depth of a foot, and pour into each Y2 ounce (a tablespoonful)
of carbon bisulphide, quickly filling the hole with dirt, and tramping
(2) Mix one part of commercial formalin with Ioo of water,
and saturate the soil with it. Use one and one-half gallons of the
mixture per square yard for a shallow seed-bed, and a larger quantity
for a deep one.
(3) Pass live steam under considerable pressure through the soil.
This method is recommended especially for greenhouses. Iron pipes
with one-sixth-inch holes every few inches, or tile drains, are laid
at the bottom of the beds a foot or two apart. The beds are covered
with straw, sacking or boards, to keep in the heat. It will be neces-
sary to keep the steam on from a half to two hours. Place some raw
potatoes on the surface farthest from the pipes. When these are
thoroughly cooked, all the nematodes will have been killed, and the
steam may be turned off.
If a field becomes badly infested, the vines should be plowed up
and burned, and the field planted, during the remainder of the year,
and also at least during the year following, with some plant that is
not affected by the worms. Among such immune, or partially im-
mune plants are: most of the true grasses, including crab-grass;
most of the varieties of corn, and of wheat; rye; some varieties of
oats; velvet.beans, and beggarweed. Iron and Brabham cowpeas
are usually resistant; onions, parsnips, strawberries and turnips are
On the other hand, the following plants commonly grown in
Florida are subject to infestation. Those most liable to a severe at-
tack come first in the list.
Most cowpeas Beets
Many weeds, including careless- Okra
weed (Amaranth) Beans
Irish potatoes Bananas
26 FLORIDA AGRICULTURAL EXPERIMENT STATION
Sweet potatoes Kale
Soy beans Papaya
Radishes Japanese persimmon
Mustard Grapes, old world
When growing any of the immune or partially immune plants
to free the land from root-knot, it is important that all weeds (and
particularly the "careless-weed," or Amaranth) should be destroyed,
as they would harbor the pests. If this is done for two years the
nematodes will have died of starvation.
It is evident that an affected tomato crop should not be followed
by any crop whose name occurs in the list of plants that are liable
tc be affected, nor should any field that has grown a crop of any one
of these plants which was known to be seriously affected by root-
knot be planted in tomatoes immediately afterwards. There are
nearly three hundred species of plants which may be more or less
infested by the root-knot worm.
This is a very common insect, which is usually to be found in
small numbers on a great variety of blossoms, including those of to-
matoes and citrus. Usually it is not sufficiently abundant in the to-
mato fields to do any harm. But occasionally (as during the spring
of 1912) it may do a great deal of
damage. It is called the Grain
Thrips, because it was first noticed
on wheat in New York. It is a
minute soft-bodied insect, about one
Stwenty-fifth of an inch long,
with orange head and thorax, and
lemon-yellow abdomen. The lat-
ter it often curls up over its back
in a threatening way when dis-
turbed. Under a lens it is seen to
have brownish-red eyes, and short
antennae with black rings on them;
Fig 12-Thrips (Euthrips tritici). s wi i
Magnified about 30 times. also short wings which are very
delicately fringed (Fig. 12). The latter look quite inadequate to carry
the insect, but this is far from being the case, as the adults fly quite
readily for a considerable distance. When disturbed, the thrips can
spring two or three inches. They are quite active creatures and crawl
about a great deal. The young (or nymphs) are very similar to the
adults, but lack the wings. This species is closely related to the pear
thrips, which does much damage in various parts of the country.
LIFE HISTORY.-This is very short, a generation occurring every
two or three weeks under favorable conditions. The eggs are laid
just beneath the surface of the plant tissue in a shallow slit.
DAMAGE.-The young, upon hatching, at once attack the tender-
est part of the blossom or bud. The stamens seem to suffer first;
but, as there is always much more pollen produced than can be used,
no particular harm is done here. If there are only a few thrips pres-
ent, say, one or two to each blossom, they usually find enough food
in the stamens and do no harm to the crop. It is even possible that
they are of service in cross-pollinating the blooms. But where there
are a dozen of them in a single bloom, they attack other parts. In-
vestigations in the tomato fields in the spring of 1912 showed as high
as twenty thrips to a single blossom. When present in such num-
bers, various parts of the flower are attacked and seriously injured,
especially the pistil. This turns black and shrivels up. Soon after,
the whole bloom turns yellow and falls off. If this is repeated for
all the blossoms on the first three or four hands, which was often the
case this year, the crop is ruinously shortened, as these first fruits
are the paying ones.
TREATMENT.-Tobacco decoctions are very effective against
this insect. The difficulty lies in reaching the thrips with the spray,
as they are under the stamens and sheltered by them. But they are
active creatures, and when the blossom is disturbed at once come out
and attempt to get away. It is this habit which enables the grower to
reach a large part of them with the spray. In spraying, therefore, care
must be taken to thoroughly cover the blossom or bud with the solu-
tion so that the insects cannot get out without getting wet by it. One
should pass down the rows rather slowly. By letting the spray play
for a second or two on each cluster or "hand," one not only ensures
a thorough drenching, but also gives the insects time to crawl out to
where the spray can hit them. One should use as much pressure as
is possible, for the double purpose of driving the liquid into the blos-
soms, and of frightening the insects out by the force of the impact
of the spray against the flowers.
Different tobacco decoctions, of which there are many on the
28 FLORIDA AGRICULTURAL EXPERIMENT STATION
market, vary much in the strength of nicotine present, and conse-
quently, in the proportions in which they should be mixed with water.
Black Leaf "40" should be used in about the proportion of one part
to from I,ooo to 1,800 of water; the weaker solutions, as Black Leaf
(2 1-3 per cent.), in about one to Ioo; while one part of home-made
tobacco extract should be used with about 10 of water. It is of ad-
vantage to put into the solution something to give it better sticking
qualities. The writer used the following mixture on tomatoes dur-
ing April, 1912, and killed about 75 per cent. of the thrips present.
This solution was previously found very effective against the orange
thrips in California.
Commercial lime-sulphur, 2 1-3 quarts
Black leaf "40", 3 1-2 fluid ounces
Water, 50 gallons
Lead arsenate or zinc arsenite can be substituted for the lime-
sulphur in case the grower wishes to kill the tomato worms or other
biting insects at the same time.
There are many species of caterpillars that go under the general
name of cutworms, but they are all naked larvae of the Noctuid fam-
ily of moths. (Fig. 13.) Most of them, when full grown, are from
one to one and a half inches long,
rarely two inches. They vary from
a dirty gray to a yellowish brown,
usually with more or less obscure
longitudinal lines (Fig. 13 a).
They hide during the day, usually
a little below the surface of the
d ground, coming out at night to
feed on whatever is to be had.
When disturbed their habit is to
curl up and "play 'possum" for a
time. When the tomatoes are
first set out, some cutworms eat
off the young plants just above the
ground. Other species crawl
into the larger vines and feed on
the young fruits. These are called
e "climbing cutworms." The fe-
Fig. 13-(From U. S. Dept. of Agr.) male moth lays her eggs (Fig.
-Cutworm (Mamestra chenopodii).
a and b, larva; c, pupa; d, moth. 14, a), (which are one-fiftieth of
BULLETIN 112 29
an inch in diameter), during midsummer in masses on the stems of
plants (Fig. 14, b), in grass land or weedy fields. The caterpillars
become half grown before going into winter quar-
ters about the roots of plants, or under boards,
etc. When this land is plowed, the food plants
are greatly reduced in numbers, and the hungry
larvae fall voraciously upon the young tomato
plants as soon as they are set out. Some are
double-brooded in this State; that is, there are
two generations each summer. The moths, as a
general rule, fly at night, and are grayish or
brownish, with lighter hind-wings, and a cor- ,
paratively thick and heavy body (Fig. 13, d).
The fore-wings commonly expand about one and
one-half inches, and have few conspicuous mark- Fig. 14-(From U.
ings except frequently lighter-colored crescentic S. Dept. of Agr.)
spots about two-thirds of the length from the tis saucia). a, egg
base (Fig. 13, e). When at rest the wings are fold- (m a g ni field ; b,
eggs on stem.
ed back over the body and arched to form a roof. eggs on
TREATMENT.-Where fields are known to be badly infested with
cutworms they should be plowed as long in advance of setting out the
crop as is possible. This will cut off the food supply and cause the
worms to starve or leave the fields, which they will have done at the
end of a few weeks. If it is not possible or desirable to plow the land
so long in advance, another method is to distribute in patches over the
surface of the plowed field (a week or more before transplanting the
tomatoes) cabbage, lettuce or other succulent vegetation which has
been poisoned by dipping it into Paris green (one pound to 50 gallons
of water), or the bait crop can be (as recommended by Smith) sprayed
with the poison before cutting. This will need to be renewed every
two or three days. It, of course, should be placed in the field towards
evening. The cutworms, finding nothing else to feed on, will eat this
material and be killed.
A poison bait that has been used satisfactorily by truck-growers
in Florida is made by mixing bran with Paris green in the proportions
of one pound of the latter to 50 of bran. It should be mixed dry, and
then moistened with enough water (to which a little sugar or syrup has
been added) to make the whole mass wet but not sloppy. A little of
this can be placed near each plant which it is desired to protect. The
worms seem to prefer this bran to even green vegetation. This rem-
edy can be used when it is impossible to use either of the two preced-
ing ones. It will require about ten pounds of the bait per acre. In New
30 FLORIDA AGRICULTURAL EXPERIMENT STATION
Zealand they use salt instead of sugar or syrup in the water with which
the bran is moistened. Just enough salt is used to enable one to taste
it in the water. Some truck-growers prefer to use cottonseed meal
instead of bran. In this case they use about a teaspoonful of Paris
green to a quart of meal.
(Phlegethontius quinquemaculata, and P. se.vta.)
Because of their large size, these insects attract the attention of
the grower, but the total amount of damage actually done to the
tomato crop is far less than in the case of any of the preceding in-
sects. The moths of this family (Sphingidae) are known as "sphinx
Fig. 15-(From Bul. 48)-Moth of southern horn-worm
Fig. i6-(From Bul. 48)-Moth of northern horn-worm
BULLETIN 112 31
moths," from a habit the larva has of elevating the front end of the
body when at rest, arching the head down a little, and remaining
perfectly immovable in this position. They are also known as hawk-
moths because of their rapid flight, and as humming-bird moths from
their habit of hovering over their favorite blossoms like those most
exquisite birds. They fly about dusk, and on very cloudy days; and
visit flowers with long corollas, such as Jimson-weed and petunias.
The body is very large, and in order to carry it the moths move their
wings with great rapidity, so that, like the birds, they also hum.
Another characteristic is the long proboscis which is used to sip the
nectar from the deepest flowers.
There are two species of sphinx moths likely to prove destructive
to tomatoes in Florida. The Southern horn-worm (P. sexta), (Fig.
15), ranges far into South America and is much the more common
one. According to A. L. Quaintance (Bul. 48, Fla. Agr. Exp. Sta.)
this worm was about six or seven times as numerous in Florida as the
other. The Northern tobacco worm (P. quinqucmaculata), (Fig. 16),
ranges farther north, and does not occur much south of the United
States. The adults can be distinguished by reference to the ac-
companying figures. The larvae may be told apart by the color of the
horn, which is black in P. quinquemaculata and red in P. sexta. The
stripes on the sides are also different, being distinct V's in the former.
It is not, however, of any particular importance that the grower
should distinguish between them, as the damage done, and the treat-
ment, are the same for both. The adults lay grayish-yellow, smooth,
spherical eggs in the spring, singly on the lower surfaces of leaves.
The eggs measure amount one twenty-eighth of an inch in diameter,
and hatch in three days into small green larvae. These eat raven-
ously, grow rapidly, and molt five times during the three weeks that
are necessary for their growth. During this time a single worm will
nearly strip a tomato plant of leaves. When full grown, the larvae
of horn-worms (Fig. o1) are three or four inches long. Near the
posterior end there is a curved spine which has given the larvae the
name "horn-worm." This 'is
wrongly supposed by many to ~ g$ 'K""
be a poisonous sting, but the
insect is entirely harmless. "2
When the "worms" are full .
grown they enter the ground ._
to a depth of three or four
inches, and change to the dark g. th-(Frorn- 48)-Pupa of
32 FLORIDA AGRICULTURAL EXPERIMENT STATION
red-brown pupae. The projecting tongue-case is characteristic of the
pupae of this family of moths and enables them to be told at a glance;
it suggests a handle to the pupa. (See Fig. 17.) The pupae from the
first brood of larvae appear in North Florida in July.
NATURAL ENEMIES.-The horn-worms are held in check pretty
well by their natural enemies. Among the latter are tachina flies,
which lay their eggs on the caterpillars, and also a minute hymenopter-
ous insect (Apanteles congregatus). The eggs hatch into minute
grubs which burrow into the worm and live on its fatty tissue, but
avoid the vital organs, grow to full size, and then emerge to form their
pupae on the outside of the host. (See Fig. 18.) These parasites
have been given prominent mention, because it is important that these
parasitized specimens be not crushed or otherwise destroyed. Para-
sitized worms should be left carefully alone, as the caterpillars will
Fig. r8-(From Bul. 48)-Sphinx larva parasitized by Apance-
surely die, leaving the parasites to hatch out. If the host is crushed
or destroyed, one also kills the parasites, our allies. This is, of course,
true of any parasitized insect. Never kill a parasitized insect.
Among the enemies of these, and, indeed, of almost all, caterpil-
lars, are wasps, which use the worms as food for their young. They
are among the most useful of the grower's allies, and should be pro-
tected by him instead of being wantonly destroyed.
REMEDY.-Because of their comparatively small numbers and
large size, hand-picking the larvae (which are usually readily seen, or
at least their presence indicated by their droppings) is usually certain
to keep them down. Should they become locally serious at any time
the vines may be sprayed with lead arsenate or zinc arsenite. Paris
green may also be used.
This is a disease of the tomato characterized by general fuzzi-
ness. In its first stages it may be recognized from the following de-
scription by P. H. Rolfs in Bul. 91, Fla. Agr. Exp. Sta.
If one is standing in a tomato field shortly after sunrise, or near sunset,
and looking across the field in the direction of the sun, the plants which are
attacked will be easily distinguished from the others in the field by a peculiar
white, fuzzy appearance of the upper portion of the stem.
In spite of its name "mold," it is not caused by a fungus para-
site, but, as was determined by P. H. Rolfs in 1892, by a small mite,
closely related to the rust mite of citrus. This mite is almost peculiar
to Florida, for, although it occurs as far north as South Carolina, it
is rarely seen as a tomato pest outside of this State.
The remedy is the same as for its close relative, the mite of cit-
rus; that is, sulphur. In this case the sulphur is best used as a
spray, which must be thoroughly applied. The formula (as given
in Fla. Agr. Exp. Sta. Bul. 76) is:
Caustic soda (98 per cent.), io pounds
Flowers of sulphur, 20 pounds
Water, 20 gallons
Mix the sulphur in cold water to a thick paste, add the soda, and
as it boils add water gradually to make twenty gallons. This water
should be added fast enough to prevent burning, but not fast enough
to stop boiling. The result will be a dark coffee-colored liquid. Strain
through a fine-meshed cloth or spray-strainer. Keep in tightly-corked
jugs. Mix one-half gallon of this stock solution in 40 gallons of
water when ready to use. Other good remedies are: lime-sulphur
solution, dry sulphur, and dry sulphur and lime.
TOMATO APHIS, OR PLANT LOUSE
(Megoura solani Thomas.)
DESCRIPTION AND LIFE HISTORY.
It is probable that this insect (see Fig. 19, the cabbage Aphis, a
related species), like most aphids, passes the winter in the egg stage.
These eggs are very small and hard to find. In the early spring they
hatch into the nymph. This is a pale green bug with a dark green
stripe along the middle of the back. The head is lighter in color, with
brownish eyes. On the back near the posterior end are two horn-like
34 FLORIDA AGRICULTURAL EXPERIMENT STATION
projections, the wrongly-called "honey tubes." The insects are wing-
less, and generally remain so throughout life. They grow very rap-
idly, especially in warm, moist weather, when they may be able to
produce youig in a week or
even less. The individuals of
this first brood, known as the
A- 1 "stem mothers," are partheno-
'. *' genic; that is, they produce
/ young without being fertilized.
r'"''1 Indeed, no males are produced
.. at this time of the year.
6 Strictly speaking, the stem
Fig. g1-(From U. S. Dept. of Agr.)- mothers are without sex, as
Plant louse or aphid (Aphis brassicae). they are not sexually developed
b, wingless form; a, winged form. f
females. They are also vivip-
arous; that is, they bring forth the young alive, and at a rapid rate.
One aphid of another species has been seen to produce eight young
in, 24 hours, and one can easily find family groups consisting of a
single large aphis surrounded by a dozen or more smaller ones, her
progeny. It is thus seen that the powers of reproduction of aphids
are enormous. They are eagerly preyed upon by a host of predaceous
insects, among the more important of which are lady beetles (both
larvae and adults), and the young of the lace-winged flies, and of
syrphus flies. Among higher animals the small birds, such as wrens,
and especially warblers, destroy immense numbers. The common
small lizards, and probably toads and small snakes, are efficient
friends of the grower. Fungus enemies also kill many.
From time to time wings are developed on the adults. (Fig. 19, a).
These serve to spread the species from plant to plant much more rap-
idly than is possible with the crawling individuals. Toward winter,
males and true females are produced. The fertilized females lay the
winter eggs from which develop the stem mothers of the next year.
In the warm climate of Florida, especially the southern part, however,
the viviparous parthenogenic reproduction described above can un-
doubtedly continue all winter.
TREATMENT.-Kerosene emulsion is a standard remedy against
all plant lice. To make this, dissolve one-half pound of hard soap
in one gallon of soft water and boil. Warm two gallons of kerosene
(setting the dish containing it in a vessel of hot water is a safe
method), and add the boiling hot suds to it away from the fire. Stir
violently, or better, churn with a force pump for a few minutes. It
should first get milky in appearance, then creamy, and finally a soft,
butter-like mass is obtained, which, when cold, will stick to glass
without oiliness. This stock emulsion can be kept for some time.
When wanted for use it should be diluted with from o1 to 2o parts of
water. If soft water cannot be readily obtained, soften the water by
the addition of soap, soda, or borax. A dilution of one part of kero-
sene emulsion to ten of water will usually not burn the plants. How-
ever, as the strength that a plant can endure depends much on its
condition of growth and the weather, it is best to experiment a little,
and if the above strength is harmful, dilute it down. A strength of
one to twenty is sometimes quite effective against plant lice.
Whale-oil soap, or fish-oil soap, in the proportion of one pound
to six gallons of water, is effective.
Fine tobacco dust is very effective against aphids if applied when
.the plants are wet with rain or dew. As in the case of sprays, this
should be applied thoroughly. The finer the dust, the more effective
it will be. In order to be of any value, most contact insecticides, or
vapors they give off, should be able to enter the fine breathing pores
or spiracles of the insects. If too coarse to do this, they will be use-
less. The tobacco can be applied in the form of a decoction. To
make this, boil one pound of leaves, or two of stems or dust, in two
gallons of water. Many useful tobacco extracts are on the market.
One of these that is well spoken of is "Black-leaf" (Ky. Tobacco
Products Co., Louisville, Ky.) One part of it is used in from 60 to 65
of water. "Black-Leaf 40" is a very efficient solution, even when used
as dilute as one part in eighteen hundred of water.
Flea-beetles often attack young tomato plants while yet in the
seed-bed, eating the leaves and shoots. They get their name from
their ability to spring a good distance as compared with their size.
The eggs are laid two or three in a bunch near the roots of the plant
in a cavity gnawed out by the female for the purpose. From these
eggs, larvae hatch out, which grow, like other beetle larvae, into rather
long, fleshy worms that may be distinguished from the larvae of but-
terflies or moths by the absence of thick, fleshy false feet, having but
three pairs of the short true feet. These larvae live on the roots of
different plants. When full grown they form earthen cocoons where
they stay two or three weeks, and then issue as adults. These are oval
mostly shiny black beetles only about one-tenth of an inch long. Bor-
deaux mixture is a very efficient remedy for the adult flea-beetle. (It
at the same time forms a good preventive for fungus disease.) Their
36 FLORIDA AGRICULTURAL EXPERIMENT STATION
depredations may be largely checked by dusting the plants with ashes,
air-slaked lime, or tobacco dust, or spraying with tobacco decoction.
Kerosene emulsion, mentioned as a remedy for aphids, may be used,
especially around the roots, to destroy the larvae and eggs.
There are a number of insects not particularly partial to the to-
mato, and which can therefore hardly be considered as insects charac-
teristic of this plant, which, however, occasionally do damage. They are
mostly of widespread distribution, and infest many species of plants.
BLISTER BEETLES (Epicauta spp.).-These insects, also known as
"Spanish flies," or "old-fashioned potato bugs," sometimes become suf-
ficiently numerous to strip the leaves from quite an area of their fa-
vorite foods, such as tomato, potato, beet and to-
bacco. The adults (Fig. 20) move in large com-
panies, which can strip a'number of plants in a few
hours. It is only the adult beetles that injure vege-
tation. The young feed either on the honey and
eggs of wild bees, or on the eggs of grasshoppers,
g. (Frm U in which latter event they do much good. In view
Fig. 2o--(From U.
S. Dept. of Agr.) of this fact, it is probably as well to make no very
-B ister beetle strenuous attempt to destroy them unless they oc-
cur in such excessive hordes as to threaten serious
damage. Several species of blister beetles are partial to certain of
our wild plants, such as asters and golden-rods.
The best remedy is probably lead arsenate, or zinc arsenite. The
spraying should be done very thoroughly, so as to cover every por-
tion of the plants in order to discourage feeding. The beetles take
fright readily, and an old remedy is to drive them from a small patch
by means of leafy branches, brooms or switches.
WHITE-LINED MORNING SPHINX (Celerio lineata).-Its larvae
occasionally infest the tomato, although its favorite food plants are
certain weeds, especially of the purslane family. It belongs to the
same family as the Tomato Sphinx, which it resembles in general
shape but is brighter in color.
The same methods of hand picking and spraying with arsenate
of lead are recommended for this species also.
SEMI-TROPICAL ARMY WORM (Prodenia eridania).-During the
summer of 19o9 an outbreak of this caterpillar occurred in different
places in Florida (Bul. 66, U. S. Dept. of Agr., Bur. of Ent.). The
name "army-worm" is given to certain caterpillars from their habit of
migrating in large companies. This insect is related to the cut-worms
and the Southern Army worm or grass worm (which also occasionally
attacks tomatoes). The fore-wings of the adult moth are gray with
brown markings, and the hind-wings are pearly white. The caterpil-
lar has five longitudinal yellow stripes.
Spraying with lead arsenate or zinc arsenite will prove effective.
GRASSHOPPERS.-These also attack the tomato in common with
other plants, and in occasional years there is an outbreak of a serious
nature. There are many species.
The treatment is practically the same for all of the species. In
the tomato field the best method is probably to use one of the poison
baits. The most successful seems to be the following "Minnesota
Sodium arsenite (commercial), I pound
Horse manure, 120-I5o pounds
Cheap molasses, I pint
The arsenite and the molasses should be dissolved in enough
water to moisten the mass.
It has been found that field crops may be protected and the grass-
hoppers killed by spraying with the following:
Commercial arsenite of soda, 3 pounds
Molasses, I I-2 gallons
Water, i80 gallons
It takes about 50 gallons per acre of this spray, at a cost, for
materials, of 30 cents. The insects are not killed at once, but become
sick, and die in about 24 to 36 hours.
An older remedy is the poisoned bran, recommended for cut-
worms. Where it is practical to do so, it is well to allow turkeys to
roam in the field. They will be found a most efficient help, as they pre-
fer grasshoppers to almost any other food. Most of our larger wild
birds, such as robins, catbirds, mocking-birds, shrikes, sparrow-hawks
and quail, are a great help to the farmer, and should receive every en-
couragement to nest on the premises. They are particularly valuable
at the nesting time. Nearly all birds feed their young largely or ex-
clusively on insects.
SUCK-FLY (Dicyphus minimus Uhler).-This small bug, which is
a serious pest of tobacco, occasionally attacks tomatoes and egg-plants
in the early fall (Fla. Agr. Exp. Sta., Bul. 48). The adult (Fig. 21)
is about one-eighth of an inch in length. A. L. Quaintance found that
a strong tobacco infusion was the best remedy. One pound of to-
bacco to every gallon of water was found necessary to kill them.
38 FLORIDA AGRICULTURAL EXPERIMENT STATION
Boil thoroughly for an
hour, and strain. The
decoction will keep two
or three days only.
Here, as elsewhere,
clean culture is one of
the best preventive.
Clean up and burn all
plants of both tobacco
and tomato as soon as
"'' the crop is harvested.
Fig. 22 shows the
young (or nyniph).
_______WHITEFLY OF TO-
MATO (Aleurodes ta-
Fig. 21-(From Bul. 48)-Suck-fly (Dicyphus ba This relative
minimus). Magnified 14 times. baci).- This relative
of the too well-known
citrus whitefly occasionally attacks tomatoes. Kerosene emulsion is
recommended, as well as destruction of badly infested vines.
BUGs.-In common with many other plants, the tomato suffers
from the attacks of a number of bugs which suck the juices of the
plant. Among them are the green soldier bug, or pumpkin bug (Ne-
zara hilaris), the stink-bug (Euschistus variolarius), and the leaf-foot-
ed plant-bug (Leptoglossus phyllopus, Fig. 23).
Kerosene emulsion, or tobacco decoction, will prove effective
against the young nymphs, and it is at this stage that they should re-
ceive the attention of the grower.
When they have become adults it
is rather more difficult to kill
them. Then hand-picking, or
knocking them off into a pan of
kerosene in the early morning or
on cool days when they are slug-
gish, is about the only practical
method of dealing with them.
Besides these larger bugs, :-:
tomato plants are often attacked
by a number of smaller, more del- tl. ;
icate bugs. Among them may be !.'!
mentioned the tarnished plant bug, "
a greenish-brown insect about 2 m B. 4
Fo ig. 22-(From Bul. 48)--Nmph of
one-fourth of an inch long; the suck-fly. Magnified 14 times.
sharpshooters, and the leaf-hoppers. One of the latter is the "de-
structive leaf-hopper" (Cicadula), a brownish bug about one-fifth of
an inch long. This lays its eggs in the tender branches, causing them
to wilt. These wilting branches may be
destroyed with the contained eggs. The
tobacco sprays will prove effective against
any of these smaller bugs even in the
The Colorado potato beetle (Leptino-
tarsa decemlineata) is becoming quite
Common on potatoes in West Florida.
During the summer it lives on wild night-
shades, but occasionally attacks tomatoes.
This rather large beetle may be readily
recognized by the five conspicuous black
lines which run lengthwise'of each yellow
Fig. 23- ro U. S. Dept. wing-cover and give to the insect its spe-
Fig. 23- (From U. S. Dept.
of Agr.) Leaf-footed cific name. The best remedy, if the
plant bug (Leptoglossus beetles become serious, is a solution of
lead arsenate, one pound to from seven
to ten gallons of water. Where there are but few, hand picking will
prove to be more practical.