PRESS BULLETIN 206
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
By J. R. Watson
This plant louse is commonly called the Melon Aphit, and frequently in
Florida the "Hessian fly," although it is a very different insect from the true
Hessian Fly which devastates the wheat fields of the Central States. It is
an insect that is easily overlooked in the early stages of the outbreak, be-
cause of the small size of the individual bugs, and the fact that they remain
on the underside of the leaves. As a result the grower too frequently fails
to notice their presence until the curling, wilting, and dying of the. leaves
There are four effective measures that may be taken to keep these bugs
in check: spraying; fumigation; dusting; and clean culture;
The ordinary grower will probably find that the most satisfactory method
of dealing with the outbreak is .to spray with a soap and tobacco decoction.
He will probably find it cheaper to buy his tobacco extract already made;
but if a supply' cannot be quickly obtained when the first signs of aphids
appear, it is better to make one's own than to delay action. Place tobacco
stems and refuse in enough water to cover them well, and boil gently for an
A good formula is the following: dissolve one and a half pounds of soap
in one-half gallon of water, add four-fifths of a pint of "Black-Leaf 2 and 2-3"
and boil for five minutes; then dilute to five gallons. There are many to-
bacco extracts on the market which vary in strength, but most of them will
need to be used in a dilution of about one part to fifty of water to kill this
aphid which is more resistant than most others. "Black Leaf 40" is a
strong extract of nicotine sulphate, and one part of this in 1800 of the spray
will suffice to kill. With the home-made decoction use about one part to five
of water; or one gallon in the above formula instead of the "Black-
Kerosene emulsion and whale-oil soap are fairly satisfactory remedies
for aphids on most plants, but for this species feeding on cucurbits, particu-
larly when on young cucumbers, a dose strong enough to do effective work
is apt to burn the plants. With the soap-tobacco spray there is no danger.
Harch 29, 1913
(One should have a nozzle of the Vermorel type, with an elbow to get under
Fumigation has been carried on successfully in some parts of the United
States. In the garden this can be done under inverted tubs or other tight
receptacles; but the large grower, if he resorts to this.means of fighting the
aphids, had better make about ten fumigating frames out of two by three-
quarter inch strips. They should be 1 by 4 by 6 feet, and covered with mus-
lin cloth which has been soaked in linseed oil. The cloth should hang below
the frame, so that earth can be thrown on its edges to make the frame
gas-tight. The safest fumigating material is one of the prepared tobacco
papers. These are burned under the frame, which is left over the vines for
about fifteen 'minutes while the operator prepares' the other nine frames.
Hydrocyanic acid may be used by the operator against the insects, but he
should be careful not to inhale the poisonous gas himself. For 50 cubic
feet, use one-third ounce of sulphuric acid added to one ounce of water in
an earthenware dish, and drop into it one-third ounce of potassium cyanide.
Carbon bisulphide can also be used, but the operator must lay aside his
pipe, as the gas is very inflammable. Use about a teaspoonful for each cubic
foot of space.
To get the best results, fumigation should be done on cucumbers in the
morning when the plants are damp.
Fine tobacco dust, placed about the young plants when they are wet with
dew, is often effective in preventing an outbreak; but it is considerably
less effective than the sprays when the aphids have had much of a start.
Nevertheless it is a quick and handy method of treatment, and if used in
time may suffice.
Besides cucurbits, the aphids feed on cotton, citrus, beets, tomatoes,
and, especially in winter, on many weeds, including careless weed, Jimson-
weed, plantain, morning-glory, dock, Portulaca, and milk-weed. It is obvious
that these weeds should be kept down, and that ground on which a cotton
crop had grown that was badly infested with aphids should not be planted
to cucurbits next year. Any infested vines should be burned as soon as
they have become useless.
Aphids have many enemies, among the most active of which are the
lady-beetles, aphis-lions, and the larvae of Syrphus flies. The last have the
size and build of blow-flies. These enemies should be encouraged, and to
that end there may be grown during the winter, on ground intended for
cucurbits, a little rape, kale, or mustard, as a trap crop. On these the cab-
bage aphids will develop, and the above-named enemies will be attracted.
SState papers please copy.