CULTURAL DIRECTIONS 283 



cially troublesome to cabbage and cauliflower. Chitten- 

 den ("Insects Injurious to Vegetables," p. 132) claims 

 that the insect has been on the increase since 1902. 



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. Slingerland observed that the fly makes its first 

 appearance on Long Island the latter part of April, and 

 that larvae were first seen in early May. From 4 to 10 

 days are required for hatching. The larva or maggot is 

 footless, shining white, sometimes 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, often boring into the 

 lower part of the root. It pupates within its own hard- 

 ened skin in soil about infested plants. The time re- 

 quired for pupation is from 15 days to 3)^ months. A 

 second brood emerges about the middle of June and 

 changes to puparia in July. The life history from this 

 time is unknown, but 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 card disks about the plants before egg 

 laying begins. (Cornell Station Bulletin 78, pp. 481- 

 574). Although effective, the making and placing of 

 these cards is tedious and the plan is not generally pop- 

 ular with extensive growers. Carbolic acid emulsion 

 (133) is the most practical means of controlling the pest. 

 It should be diluted about 30 times and applied by spray- 

 ing on the stems of the plants before egg-laying begins, 

 and repeated if necessary. Experiments made at Geneva, 

 N. Y. (New York Station Bulletin 301), show that 

 growing the plants in frames covered with cheesecloth 

 is a satisfactory method of protection before trans- 

 planting. 



364. The cabbage aphis (Aphis brassicae), also known 



