Florida Agricultural Experiment Station


 TURNIPS
 TURNIP PLANT-LOUSE (Aphis pseudo-brassicac)
 This plant-louse is very much like the cabbage-aphis with
which it is often found. It differs by being more hairy. The
remedy is the same as for the garden aphid which is also found
on turnips. (See plant-lice under cabbage, page 144.)
 Other insects attacking turnips are: Flea-beetles (see un-
der beets, page 136); and root-maggots (see under cabbage,
page 146).
 WATERMELONS
 MELON-APHIS (Aphis gossypii)
 This plant-louse in Florida is commonly called the Hes-
sian fly," altho it is a very different insect from the true Hes-
sian fly which devastates wheat fields in the Central States. It
is the most serious enemy of watermelons in the State and does
great damage. Not infrequently, it destroys whole fields of
many acres before a single melon has been shipped. It is a
dangerous pest of cucumbers, cantaloupes, squashes, gourds, and
other curcubits as well as watermelons. It commonly attacks
cotton and citrus and is found on many weeds and other plants.
Next to the garden aphid it is the most common and wide-
spread aphid in Florida.
 The life history and enemies of this species are about the
same as those of the garden aphid. (See cabbage pests.)
 Control.-There are four measures that are effective in
keeping these bugs in check: spraying, fumigating, dusting,
and clean culture.
 Spraying.-The grower will probably find that the most
satisfactory method of dealing with an outbreak is to spray
with a soap and tobacco decoction. He will probably find it
cheaper to buy the tobacco extract already made, but if a sup-
ply cannot be quickly had when the first signs of aphids appear,
it is better to make his own than to delay action. Tobacco
stems and refuse are placed in enough water to cover them
well and kept at a temperature just below boiling for an hour,
or allowed to soak over night. The solution should then have
the color of strong tea. To keep this more than a day or two, add
an ounce of salicylic acid to each four gallons. Before use, it is
diluted with 10 parts of water.
 The ready-made tobacco decoctions, of which there are
many on the market, vary much in the amount of nicotine pres-
ent, and consequently in the proportions in which they should