Bulletin 125 December, 1914
UNIVERSITY. OF FLORIDA
Agricultural Experiment Station
ROOT-KNOT AND "WHITE MOLD"
J. R. WATSON
Fig. 15.-A horn-worm of tomato (slightly reduced).
The Station Bulletins will be sent free upon application to the Experiment
THE E. O. PAINTER PRINTING CO., DELAND, PLA.
Boll-Worm, or Tomato Fruit-Worm -------- ------------------- 57
Root-Knot ----------------------------------------------- 62
Thrips ------------------------------------------------------ -- 64
Cutworms ---------------------------------------- 66
Horn Worms ------------------------------- ----- 68
White Mold ----------------------------------- ---- 71
Aphis, or Plant-Louse -------------------------------------- 72
Flea-Beetles -------------------------------------------------------- 74
Miscellaneous Insects -------------------------- ------ ------ 74
Blister-Beetles ----------------------------- --------------- 75
White-lined Morning Sphinx ----------------------------------------- 75
Army Worms ---------------------------------------- 75
Grasshoppers ----------------- ---------------- 76
Suckfly ------------------ ---- ------------------------- 76
Tomato Whitefly --------------------- ----- ------- ------ 77
Plant Bugs --------------------------------------- 77
TOMATO INSECTS, ETC.
J. R. WATSON
BOLL WORM, OR TOMATO FRUIT WORM
This insect is the most serious, pest of the tomato in Florida. 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 de-
structive to cotton, being -
then known as the boll
EGGS. These are
whitish, oval in shape, ,
about one-twentieth of r
an inch in diameter, and, a,
as shown in Fig. 16, are
prominently ribbed. They
are found scattered here
and there over the food
plants, to which they are
fastened by a white, / d
sticky secretion. (Fig.
,sticky secret. (Fi. Fig. 16.-(From U- S. Dept. of Agr.)-Boll-
t6, b, is a view of the egg worm, or tomato worm, or corn-ear worm
from above; Fig. 16, a, (Heliothis obsoleta) : a and b, egg (enlarged);
from one side.) c, larva; earthen pupa-case; e and f, moth
from one side.) (natural size.)
c). From the egg there hatches out in a few days a small cater-
pillar 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 I14 to 2 inches long.
58 Florida Agricultural Experiment Station
PUPA.-When full grown, the larva descends the plant and
burrows 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. 16, 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. 16, f and e), which varies from dusky yellow to gray-
ish. The markings on the wings are also variable. The distance
across its outstretched wings is from I 2 to 2 inches. Unlike most
moths, it may fly in broad daylight; but the eggs are usually de-
posited towards evening.
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, pre-
ferably on corn; but if corn is not to be had, she will choose toma-
toes, and occasionally other plants, such as peas, beans, squashes
and tobacco. 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 become hard, they are not so much relished, and then
the caterpillars attack cotton eagerly, eating into the young and
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
themselves 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
Bulletin 125 59
spoil two or three tomatoes per day, and thus do much more damage
than would be represented by the amount of food actually consumed.
ARSENICALS.-While feeding inside a good-sized tomato, the
caterpillars are, of course, out of reach of arsenicals; but their rest-
less habits offer the grower an opportunity to get at them. They
rarely remain in one fruit until their growth is completed; but,
after feeding in it for a day or so, crawl out and attack another.
While making their way into fresh tomatoes, they are in a position
to be poisoned by any arsenical with, which the fruit has been
sprayed. Especially when the first fruits are small, the chances for
poisoning the insects are good. The worms are not able, because
of the small size of these fruits, to eat their way inside, but remain
on the outside, and may eat out sections of several in a single day.
These first fruits are the most valuable part of the crop, and thus
we have an additional reason for applying poison at this time. A
third reason for applying the arsenicals quite early, when the very
first fruits are the size of marbles or smaller, is that at this time
there can be no possibility of damaging the sale of the fruit. By
the time the fruit is ready to pick, the expansion due to growth
will have destroyed all signs of the spray, even if there has been
no rain. The chances of poisoning the consumer, even if the fruit
is sprayed only a day or so before picking, are negligible. Using
lead arsenate at the rate of two or three pounds to 50 gallons of
water, the amount that would be left on each fruit would be so small
that the stomach of the consumer could not hold enough tomatoes
to enable him to get an injurious dose of the arsenical, even if the
tomatoes were not washed before eating. However, any trace of
the spray on the fruit at the time of marketing would probably
hurt its sale. For this reason we recommend that the spraying be
discontinued a week or ten days before the first picking. The first
spraying should be given when the earliest tomatoes are the size
of small marbles. A week later, if there is no rain, a second spray-
ing can be given. Should it rain shortly after the first spraying,
it would doubtless be advisable to apply a second spray within three
or four days after the first. Even a single spraying will greatly
reduce the percentage of infestation.
In some experiments conducted by the writer during the sum-
mer of 1914, the plants were sprayed but once, when the earliest
fruits were about half grown, using lead arsenate paste at the rate
60 Florida Agricultural Experiment Station
of two pounds to 50 gallons of water. Careful counts made one
week later showed that the percentage of wormy fruit on the un-
sprayed rows was nearly twice as great as on those sprayed. At the
date of spraying, the sprayed rows showed a higher percentage
of infestation than the ones not sprayed, on account of their proxi-
mity to some maturing corn. In other words, one spraying with
lead arsenate killed half the worms present.
We recommend that, in using the lead arsenate spray, two
pounds of lime be added to the liquid to prevent burning.
The newer arsenical, zinc arsenite, has several advantages over
lead arsenate for this work. It is cheaper, in that one uses only
one pound to 50 gallons of water. It washes off more readily, and
therefore there is less danger of any being left on the fruit at
picking time. It is decidedly less poisonous to man than is lead
arsenate, and therefore injurious effects are even less probable. If
one is spraying with Bordeaux mixture at this time, the arsenical,
either lead arsenate, zinc arsenite or Paris green, may be added to
CORN AS A TRAP CROP.-This insect prefers corn, especially
sweet corn, to any crop grown in Florida. During the summer of
1914, some successful results were obtained in the use of sweet corn
as a trap crop. 'On one small plot of tomatoes planted next to some
sweet corn which was just coming into silk when the earliest to-
matoes were forming, there were no worms at all, while a field
a quarter of a mile away averaged 20 per cent infested fruit. Ob-
servations would indicate, however, that the corn must be planted
very close to the tomatoes to provide protection. We recommend
that ten to twenty rows of tomatoes alternate with two rows of
corn. If a single row of corn is planted across the field, it usually
does not get thoroughly pollinated, and the ears will not be suf-
ficiently attractive to prevent the caterpillars from wandering to
the tomatoes. Also the corn must be planted at such a season as
to be in an attractive condition when the first tomatoes are form-
ing, that is, it must have young silks, otherwise the insect prefers
the tomatoes. This corn must be destroyed before it has matured
enough to be unattractive to the worms, otherwise it will increase
rather than decrease the number of worms in the tomatoes. Many
larvae will crawl from the corn to the tomatoes; and many moths,
whose larvae matured on the corn, will emerge from the cocoons
and fly to the tomatoes. The corn can be left until the ears are
sufficiently mature for roasting purposes, but by no means should
they be left to ripen in the tomato field.
Bulletin 125 61
All wormy fruit should be picked and removed from the field,
and so disposed of as to destroy the larvae. Stock, hogs, and also
chickens, will eat a limited amount of these wormy tomatoes, espe-
cially if they do not have access to other green food. Where the
acreage of tomatoes is large, the most practical method of dispos-
ing of these wormy fruits is to dump them into a pond, or 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 prac-
tice of dumping the wormy and cull fruits beside the packing
house or along the roadway cannot be too severely censured. A
large percentage of the worms will complete their development in
the pile, pupate in the ground, and later come out as moths to
augment later infestations. 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, as the caterpillars will more quickly leave the detached fruit
and attack a new one. Wormy tomatoes can perhaps best be sorted
out at the packing house. If these caterpillars are destroyed it will
greatly reduce the number in succeeding generations. This has
been thoroughly proven by experiments on a large scale. In one
conducted by Director P. H. Rolfs, the wormy tomatoes were care-
fully 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 favorable weather
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, but other insects,
and fungus diseases as well. Growers sometimes object to burn-
ing old plants, on the ground that they are destroying so much fer-
tilizer which would be returned to the soil by the rotting of the
plants. While it is true that some of the organic matter would be
destroyed, the loss is infinitesimal in comparison with that resulting
from the injuries caused by the insects and fungi if they are al-
lowed to live over.
62 Florida Agricultural Experiment Station
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, tools, and the transplanting of infested
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 infesta-
tion. 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) :
(I) Punch eight or nine holes per square yard into the seed-bed
to the depth of a foot, and pour into each '2 ounce (a tablespoon-
ful) of carbon bisulphide, quickly filling the holes with dirt, and
tramping it down.
(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 quan-
tity 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
Bulletin 125 63
be necessary 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 par-
tially immune plants are: most of the true grasses, including crab-
grass; most of the varieties of corn, and of wheat; rye; some varie-
ties of oats; velvet beans, and beggarweed. Iron and Brabham
cowpeas are usually resistant; onions, parsnips, strawberries and
turnips are slightly affected.
On the other hand, the following plants commonly grown in
Florida are subject to infestation. Those most liable to a severe attack
come first in the list.
Most cowpeas Sweet potatoes
Eggplant Soy beans
Many weeds, including careless- Peaches
weed (Amaranth) Figs
Irish potatoes Mustard
Lettuce Japanese persimmon
Pineapples 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 fol-
lowed by any crop whose name occurs in the list of plants that are
liable to be affected, nor should any field that has grown a crop of
64 Florida Agricultural Experiment Station
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.
(Euthrips tritici projects)
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 field 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 in-
sect, about one twenty-
Sfifth of an inch long,
with orange head and
thorax, and lemon-yel-
low abdomen. The lat-
Ster it often curls up
over its back in a
threatening man ner
when disturbed. Under
a lens it is seen to have
brownish-red eyes, and
Fig. 17.-Thrips (Euthrips tritici projectss. short antennae with
Magnified about 40 times.short tennae with
black rings on them;
also short wings which are very delicately fringed (Fig. 17). 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.
Bulletin 125 65
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 ten-
derest 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 present, 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. Investigations in the tomato fields in the spring of 1912
showed as high as twenty thrips to a single bloom. When pres-
ent in such numbers, 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 in that year, the crop is ruinously short-
ened, 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 so thoroughly cover the blossom or
bud with the solution that the insects cannot get out without getting
wet by it. One should pass down the rows rather slowly. By let-
ting the spray play for a second or two on each cluster or "hand,"
one not only ensures a thorough drenching, but also gives the in-
sects 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 driv-
ing the liquid into the blossoms, 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
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 io of water.
66 Florida Agricultural Experiment Station
It is of advantage to put into the solution something to give it bet-
ter sticking qualities. The writer used the following mixture on
tomatoes during 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, two and one-third quarts
Black leaf "40", three and one-half 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. Four or five pounds of whale-oil
soap may also be substituted for the lime sulphur. Flour paste
makes an excellent spreader for these tobacco extracts. Take two
pounds of cheap flour and stir it into two gallons of hot water. Add
this, paste to the 50 gallons of spray material.
There are many species of caterpillars that go under the general.
name of cutworms, but they are all naked larvae of the Noctuid
family of moths. (Fig. 18). Most of them, when full grown, are
I from I to i Yz in. long. They vary
from a dirty gray to a yellowish
brown, usually with more or less
obscure longitudinal lines (Fig.
18, a). They hide during the day,
d usually a little below the surface
"of the ground, coming out at
night to feed on whatever is to be
had. When disturbed their habit
is to curl up and "play 'possum"
b 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 "climbing cutworms."
Fig. I8.-(From U. S. Dept. of Agri.) The female -moth lays her eggs
-Cutworm (Mamestra chenopodii).
a and b, larva; c, pupa; d, moth. (Fig. 19, a), (which are one-
Bulletin 125 67
fiftieth of an inch in diameter), during midsummer in masses on the
stems of plants (Fig. 19, b), in grass land or weedy fields. The
caterpillars become half grown before going into
winter quarters 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 to-
mato plants as soon as they are set out. Some
Share 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
S. brownish, with lighter hind-wings, and a com -
paratively thick and heavy body (Fig. 18, d).
The fore-wings commonly expand about one and
one-half inches, and have few conspicuous mark-
Dept. of Agr.) wings except frequently lighter-colored crescentic
-Cutworm (Agro- spots about two-thirds of the length from the
tis saucia). a, egg base (Fig. 18, c). When at rest the wings are
eggs on stem. folded back over the body and arched to form
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 possbile. 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 vege-
tation which has been poisoned by dipping it into Paris green (one
pound to 50 gallons of water), or the bait crop can be (as recom-
mended 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 propor-
tions 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 and a pinch of salt have 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
68 Florida Agricultural Experiment Station
this bran to even green vegetation. This remedy can be used when
it is impossible to use either of the two preceding ones. It will re-
quire about ten pounds of the bait per acre.
Some truck growers prefer to use cottonseed meal instead of
bran. In this case they take about a teaspoonful of Paris green
for a quart of meal.
The worms bury themselves in the early morning, usually very
near the plant they have cut off the previous night. A little digging
about a freshly-cut plant will usually uncover the culprit, and prompt
punishment may be meted out. In a small garden patch or on a
large acreage where the numbers of cutworms are small, this method
of controlling them will be found the most practicable.
(Phlegethontius quinquemaculata, and P. sexta.)
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
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
Fig. 20.-(From Bul. 48)-Moth of southern horn-worm
Bulletin 125 69
Fig. 21.-(From Bul. 48)-Moth of northern horn-worm
most exquisite birds. They fly about dusk on very cloudy days;
and visit flowers with long corollas, such as Jimson-weed and petu-
nias. 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 most likely to prove de-
structive to tomatoes in Florida. The Southern horn-worm (P.
sexta), (Fig. 20), 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 numer-
ous in Florida as the other. The Northern tobacco worm (P. quin-
quemaculata), (Fig. 21), ranges farther north, and does not occur
much south of the United States. The adults can be distinguished
by reference to the accompanying figures. The larvae may be told
apart by the color of the horn, which is black in P. quinquemaculata
and red in P. sexba. The stripes on the sides are also different, be-
ing distinct V's in the former. (Fig. 15 represents the larva of a
closely related horn-worm, which sometimes damages tomatoes to a
slight extent.) It is not, however, of any particular importance that
the grower should distinguish between them, as the damage done,
and the treatment, 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 about one twenty-eighth of
an inch in diameter, and hatch in three days into small green larvae.
70 Florida Agricultural Experiment Station
These eat ravenously, grow rapidly, and molt five times during the
three weeks that are necessary for their growth. During this time
a single worm will strip a large tomato plant of leaves. When full
grown, the larvae of horn-
worms (Fig. 15) are three or
four inches long. Near the
posterior end there is a curved
spine which has given the lar-
vae the name "horn-worm."
This is wrongly supposed by Fig. 22.-(From Bul. 48.)-Pupa of
many to be a poisonous sting. southern horn-worm.
The insect is entirely harmless. When the "worms" are full grown
they enter the ground to a depth of three or four inches, and change
to the dark red-brown pupae. The projecting tongue-case is charac-
teristic 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. 22.)
The pupae from the first brood of larvae appear in North Florida in
NATURAL ENEMIES.-The horn-worms are held in check pret-
ty well by their natural enemies. Among the latter are tachina flies,
which lay their eggs on the caterpillars, and also a minute hymenop-
terous 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. 23.) These para-
sites have been given prominent mention, because it is important that
these parasitized specimens be not crushed or otherwise destroyed.
Parasitized worms should be left carefully alone, as the caterpillars
Fig. 23.-(From Bul. 48.)-Sphinx larva parasitized by Apante-
Bulletin 125 71
will 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 in-
Among the enemies of these, and, indeed, of almost all, cater-
pillars, 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 protected by him instead of being wantonly destroyed.
REMEDY.-Because of their comparatively small number and
large size, hand-picking the larvae (which are usually readily seen,
or at least their presence indicated by their droppings) is usually cer-
tain 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
72 Florida Agricultural Experiment Station
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 tight-
ly-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 and Myzus persicae)
DESCRIPTION AND LIFE HISTORY
It is probable that this insect (see Fig. 24, 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 projections, the wrongly-called "honey tubes." The in-
sects are wingless, and generally remain so throughout life. They
grow very rapidly, especially in warm, moist weather, when they
may be able to produce young
in a week or even less. The in-
dividuals of this first brood,
known as the "stem mothers,"
are parthenogenic; that is, they ,- .
produce young without being '
fertilized. Indeed, no males i
are produced at this time of the/
year. Strictly speaking, the '
stem mothers are without sex, Fig. 24.-(From U. S. Dept of Agr.)-
as they are not sexually devel- Plant louse or aphid (Aphis brassicae).
oped female ey ae alo b, wingless form; a, winged form.
hoped females. They are also
viviparous; 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 consist-
ing of a single large aphis surrounded by a dozen or more smaller
ones, her progeny. It is thus seen that the powers of reproduction
Bulletin 125 73
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.
24, a). These serve to spread the species from plant to plant much
more rapidly than is possible with the crawling individuals. Toward
winter, males and true females are produced. The fertilized fe-
males lay the winter eggs from which develop the stem mothers of
the next year. In the warm climate of Florida, especially the south-
ern part, however, the viviparous parthenogenic reproduction de-
scribed above can undoubtedly 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 Io to 20 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
kerosene emulsion to ten of water will usually not burn the plants.
However, 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
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
74 Florida Agricultural Experiment Station
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 much used is "Black-leaf, 40" (Kentucky to-
bacco Products Co., Louisville, Ky.). One part of it is used in from
Iooo to 1800 of water. "Black-leaf 2-3" is another tobacco extract.
Use about one part to 60 or 65 of water. These tobacco extracts are
on the whole the most safe and satisfactory remedies for aphids.
They will not injure the plants even if carelessly used. If one is
spraying the plants with Bordeaux mixture to control fungus dis-
eases, the tobacco extracts may be added to that mixture.
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 butterflies or moths by the absence of thick, fleshy false feet, hav-
ing but three pairs of the short true feet. These larvae live on the
roots of different plants. When full grown they form earthen co-
coons 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. Bordeaux mixture is a very efficient remedy for the
adult flea-beetle. (It at the same time forms a good preventive for
fungus disease.) Their 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 char-
Bulletin 125 75
acteristic of this plant, which, however, occasionally do damage.
They are mostly of widespread distribution, and infest many species
BLISTER BEETLES (Epicauta spp.)-These insects, also known
as "Spanish flies," "old-fashioned potato bugs," or "Yankee bugs,"
sometimes become sufficiently numerous to strip the leaves from
quite an area of their favorite foods, such as tomato, potato, beet
and tobacco. One species of blister beetle is shown in Fig. 25. The
species which are most common in Florida do not have the longi-
tudinal stripes. The adults move in large companies, which can
strip a number of plants in a few hours. It is
only the adult beetles that injure vegetation. The
young feed either on the honey and eggs of wild
bees, or on the eggs of grasshoppers, in which
latter event they do much good. In view of this
fact, it is probably as well to make no very stren-
uous attempt to destroy them unless they occur in
such excessive hordes as to threaten serious dam- Fig. 25.-(From U.
S. Dept. of Agr.)
age. Several species of blister beetles are partial B lister beetle
to certain of our wild plants, such as asters and (Epicauta vittata).
The best remedy is probably lead arsenate, or zinc arsenite.
The spraying should be done very thoroughly, so as to cover every
portion 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 lar-
vae 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 1909 an outbreak of this caterpillar occurred in dif-
ferent 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
76 Florida Agricultural Experiment Station
moth are gray with brown markings, and the hind-wings are pearly
white. The caterpillar 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 seri-
ous 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 "Kansas
Bran, 20 pounds
Paris green, I pound
Water, 2 gallons
Lemons, two or three
Syrup, 2 quarts
Thoroughly mix the bran and Paris green while dry, grate up
the lemons finely and then add to the water. Add also the syrup.
Dampen the Paris-green-bran mixture with the liquid until it is
moist or wet, but not sloppy. Scatter this poisoned bait about the
We have not found this bait to be successful in Florida during
the rainy summer season. At that time vegetation is so succulent that
it is preferred by the grasshopper to the bait. During the drier sea-
sons, however, it works better. It will be found to be fairly efficient
when the tomato plants are young. It is at this time that the grass-
hoppers are most apt to do damage.
An older remedy is the poisoned bran, recommended for cut-
worms. Where it is possible to do so, turkeys should be allowed to
roam in the field. They will be found a most efficient help, as they
prefer grasshoppers to almost any other food. Most of our larger
wild birds, such as robins, catbirds, mocking-birds, shrikes, spar-
row-hawks and quail, are a great help to the farmer, and should re-
ceive every encouragement to nest on the premises. They are par-
ticularly valuable at the nesting time. Nearly all birds feed their
young largely or exclusively 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. 26) is about one-eighth of an inch in length. A. L. Quaint-
ance found that a strong tobacco infusion was the best remedy. One
pound of tobacco to every gallon of water .was found necessary to
Bulletin 125 77
kill them. Boil thoroughly for an hour, and strain. The decoction
will keep two or three
days only. A strong
solution of "Black-
leaf 40," about I to
500, will probably be
found to be equal-
ly good. Here, as
elsewhere, clean cult-
ure is one of the best
preventive. Clean up
and burn all plants of
both tobacco and to-
mato as soon as the
crop is harvested. Fig.
27 shows the young
(or nymph ) Fig. 26.-(From Bul. 48)-Suck-fly (Dicyphus
or nymp.. minimus). Magnified 14 times.
WHITEFLY OF TO-
MATO (Aleurodes tabaci).-This relative Jf the too well-known
citrus whitefly occasionally attacks tomatoes. Kerosene emulsion is
recommended, as well as destruction of badly infested vines.
PLANT 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 (Nesara viridula), the stink-
bug (Euschistus variolarius),
and the leaf-footed plant-bug
(Lcptoglossus phyllopus, Fig.
Kerosene emulsion, or to-
bacco decoction, will prove ef-
"fective against the young
nymphs, and it is at this stage
that they should receive the at-
tention of the grower. When
they have become adults it is
rather more difficult to kill them.
"Then hand-picking, or knocking
Fig. 27.-(From Bul. 48)-Nymph of them off into a panof kerosene
suck-fly. Magnified 14 times. in the early morning or on cool
in the early morning or on cool
78 Florida Agricultural Experiment Station
days when they are sluggish, 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 delicate bugs. Among them may be
mentioned the tarnished plant bug, a greenish-brown insect about
one-fourth of an inch long; the sharpshooters, and the leaf-hoppers.
One of the latter is the "destructive leaf-hopper" (Cicadula), a
S 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 againstanyofthese
Ssm aller bugs even in the adult stage.
SThe Colorado potato beetle (Lepti-
Snoiarsa decem lineata) is become ing quite
common on potatoes in West Florida.
During the summer it lives, on wild
night-shades, but occasionally attacks to-
matoes. This rather large beetle may be
Fig. 28.-(From U. S. Dept. readily recognized by the five conspicu-
of Agr.) Leaf footed ous black lines which run lengthwise of
plant bug (Leptoglossus
phyllopus). each yellow wing-cover and give to the
insect its specific name. The best rem-
edy, if the beetles become serious, is a solution of lead arsenate, one
pound to from 10 to 12 gallons of water. To prevent any burning
effect on the vines it is well to add to the water a pound of quick
lime or hydrated lime. Where there are but few beetles, hand-
picking will prove to be more practical.