CULTURAL DIRECTIONS 283 
daily troublesome to cabbage and cauliflower. The in- 
sect has been on the increase in recent years. 
The adult resembles the common house fly, but is con- 
siderably smaller. It begins laying eggs early in spring, 
depositing - them on or near the stems of the young 
plants. From 4 to 10 days are required for hatching. 
'Fhe larva or maggot is footless, shining white, some- 
times tinged with yellow and when full grown is 0.32 
of an inch long. It prefers feeding on the young tender 
rootlets, but also erodes and girdles the stem of the plant, 
cften boring into the lower part of the root, causing the 
plant to wilt in the sun, and finally either become stunted 
or die. It pupates within its own hardened skin in soil 
about infested plants. The time required for pupation 
is from 15 days to y/ 2 months. A second brood emerges 
about the middle of June and changes to puparia in July. 
It is thought that the insects pass the winter as maggot, 
pupa and fly. 
Numerous preventives are recommended, but one of 
the best is to place tar paper pads about the plants before 
egg-laying begins. Although effective, the making and 
placing of these cards is tedious and the plan is not gen- 
erally popular with extensive growers. Almost perfect 
control has been secured by the use of corrosive sub- 
limate, one ounce of the crystals dissolved in 10 gallons 
of water. Two applications are made in the stems at 
the bases of the plants, y 2 cupful per plant, the first 3 or 
4 days after planting, the second 8 to 10 days later. The 
material may be applied with a knapsack sprayer, with 
nozzle removed, with a small apparatus designed for the 
purpose, or with a bucket and dipper. The cost of this 
treatment in New Jersey in 1921 was $29.25 per acre as 
compared with $39.00 for the tar pads (N. J. Station 
Circular 138). Covering the cabbage frames with cheese- 
cloth will afford protection before transplanting. 
364. The cabbage aphis (Aphis hrassicac), also known 
