Nicotine Dust for Truck-Crop Insects. 15 
a field quickly. It will dust a melon field at the rate of almost 1 
acre per hour, but is likely to use more dust than the hand machines. 
Dusting for this aphis was found to be satisfactory on all kinds 
of melons, cucumber, and squash. 
THE CABBAGE APHIS.* 
The cabbage aphis, a cosmopolitan and widely distributed pest, 
which often causes serious damage to cabbage, kale, cauliflower, tur- 
nips, and related crops, is not infrequently held in check by cold 
weather or driving rains, but in many seasons. when there is a lack 
I'ra. 5.—Dusting for the cabbage aphis. Note cloud of dust completely covering all parts 
of infested plants. 
of these conditions, the insects multiply very rapidly, which results 
in serious infestations and heavy damage to thousands of acres of 
cabbage and cauliflower. 
As with the melon aphis, it is difficult to obtain a satisfactory 
killing of the cabbage aphis by spraying, because the colonies of 
aphids are usually on the underside of the leaves, or are protected 
by the compact foliage of the growing head. Further, the aphis 
colonies cause the leaves to curl, rendering it almost impossible to 
reach them with spray. But the cloud of dust blown into the plant 
entirely surrounds it, and the fine particles drift in among the in- 
fested leaves, reaching a large percentage of the aphids (see Fig. 5). 
1 (Aphis) Brevicoryne brassicae L. 
