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increase in size unless checked by enemies or unfavorable weather. 
Both wingless and winged individuals are to be found, and tho 
there are few of the latter as compared with the multitudes of 
the former, these few winged lice are the chief means of starting 
colonies in uninfested fields. Like other plant-lice, the cabbage 
louse gives birth during the summer months to living young, with- 
out previous fertilization of the female by the male. In the fall, 
as observed by Fletcher, Garman, Ouaintance, and others, both 
sexes are produced, and eggs are deposited on the stems and leaves 
of cabbages remaining in the field. Sometimes, however, vivipar- 
ous females are found as late as midwinter, within the cabbage 
heads. 
The lice are about the size of a pin-head, soft-bodied, pale 
greenish, but completely covered with a whitish powder or bloom 
which is not unlike the bloom on cabbage leaves. 
Plant-lice injure cabbage by sucking the juices of the plant. 
When abundant, they so disfigure and stunt it, especially the 
smaller and weaker plants, that it becomes unfit for market. 
Natural Checks. — If it were not for the natural checks on its 
increase, the cabbage plant-louse would be one of the very worst 
pests with which the cabbage grower has to deal ; but wet weather 
and its insect enemies greatly restrict its multiplication. It is not 
only subject to attack by many minute parasites, but it is preyed 
upon by several kinds of "ladybird" beetles and by the larva of a 
lacewing fly (Chrysopa) , whose combined attacks greatly lessen 
the numbers of the aphids, and hold them in check. 
Remedies. — Probably the most successful method of dealing 
with the cabbage-louse is fumigation with carbon bisulfid. This 
substance was tested by us in the fall of 1908 on cabbages badly 
infested with plant-lice. Fumigation of cabbage or cauliflower 
on a commercial scale with individual covers for the plants would 
be too expensive for profit ; but an economical method is to cover 
a considerable area of plants widi large canvas or muslin sheets, 
with props at the corners and center, and wherever else may be 
necessary.* The cover being ready, dishes are placed beneath it 
containing the carbon bisulfid at the rate of a teaspoonful to each 
cubic foot of space. The edges of the cloth, which should lie on 
the ground, are covered with earth to prevent, as far as possible, 
the escape of the fumes. After forty-five minutes to an hour the 
cover may be removed. This treatment also killed the thrips and 
cabbage-worms which infested the plants, but it did not kill the 
parasites concealed in the aphid skins — which fact is greatly in its 
favor. With exposures of 20 and 30 minutes, nearly all gf the lice 
were killed; but with only 15 minutes or less, practically none were 
*The Melon-louse and other Aphids, by C. E. Sanborn. Bull. Texas .\gr. 
Exper. Station, No. 89, (not dated) page 47. College Station. 
