PRESS BULLETIN No. 113.
IorPlda Agricullural Experiment sallon.
THE MELON APHIS AND OTHER PLANT LICE.
BY E. W. BERGER.
The common cotton or melon aphis (Aphis gossypii), plantlouse, or
green fly, has been reported as feeding upon more than thirty different
species of plants. All but two or three of this number either grow wild or
are cultivated in Florida. The following list of food plants contains those
most commonly found: melons, cucumbers (and other plants of the same
family), cotton, okra, mallows, citrus, bush bean, pear, clover, strawberry,
careless weed, wormseed. morning glory, spinach, begonia and Jamestown
A good grade of tobacco dust applied dry by hand or by a powder
bellows or blower, while the plantss are moist with dew or rain, or applied
as a decoction in water, is regarded by many in Florida as the best direct
remedy for all kinds of aphids. When applied by hand the dust should be
thrown so that it will strike forcibly the parts of the plants where the aphids
live. In the case of cucumbers and similar crops it is quite important ane
yet difficult to get much of the dust to lodge on the under side
yet after some practice this can be accomplished in a measu
the dust a strong throw sideways. Tobacco decoction is made b
pound of tobacco leaves, stems or dust in three gallons of water
used stronger if necessary. The liquid extracts of tobacco on
are also useful against plantlice and other softbodied insects.
dry, the finer the dust the more efficient it will be: it will adhere better
when fine, and is more likely to lodge in the breathing pores and other
vulnerable parts of the insect than a coarse dust. One should purchase a
good grade of tobacco dust, preferably some standard brand. Cheap to-
bacco dust is likely to be useless, having been leached or adulte'ated.
Kerosene emulsion is regarded by some as the standard remedy for
plant lice. Dissolve 1/lb. of soap in a gallon of water, and when boiling
hot add two gallons of kerosene (away from the fire), and stir or otherwise
agitate violently for ten to fifteen minutes. For use against plantlice dilute
this with 15 to 20 parts of water.
Whale-oil soap, one pound to 6 gallons of water, is stated to kill readily,
and is frequently employed as a spray against plantlice. If the kerosene or
whale-oil soap injures the leaves add more water. Other soaps and soap
powders have been used with good effects.
Xwi~ch 27, 1909.
For spraying such flat-lying plants as melons and cucumbers, a short
extension rod with the nozzle on the upturned end of an elbow is necessary
in order to spray the under surface of the leaves where the aphids princi-
pally live. Some have found it more effective to have one person lift the
vines while another did the spraying, than to use the upturned nozzle.
Again, the vines could be turned over on the ground and sprayed, and turned
back again when finished. The last two methods are not especially adapted
for extensive work, but will be found useful in the home garden.
When we know which plants are subject to infestation by aphids we may
save ourselves trouble and disappointment in regard to the rotation and lo-
cation of certain crops. It is evident for instance, that it may be unwise
practice to plant cucumbers, melons, cantaloupes, or other crops likely to
become infested by Aphis gossypii, near citrus trees. These latter may be
harboring some of these aphids, and the result might be a rapid infestation
of the crop.
Aphids live over on wild plants from season to season; it is, therefore,
evident that much may be accomplished by a thorough cleaning up and
burning-over of the ground immediately adjoining the field which is to be
occupied by a crop subject to attack. While such a procedure might not
altogether prevent the infestation, it would greatly delay it and reduce it
in amount. The vegetation on the ground to be planted fully
plowed under, and any green stuff left uncovered sho d and
buried or burnt, to insure the destruction of all aphids.
When plants begin to show the effects of an att it is
usually too late for remedial measures to be effective. re, im-
portant that crops known to be subject to serious injury ularly
inspected at intervals of a few days, and the first o nce of
aphids should be the signal for an insecticide campaign. would
have everything ready to act at once, since one week's
spent in getting the necessary insecticides and machines
of a crop.
State papers please copy.