142 INSECTS INJURIOUS TO VEGETABLES 



cess, and arsenicals should be a^Dplied when possible to the lower 

 surface of the outer leaves to destroy all the insects. If the 

 first generations could be killed off there would be less difficulty 

 in keeping the insect in subjection. Paris green mixed with 

 lime or other diluent has been used dry with some success, but 

 is less efficient than for the imported cabbage worm. Dry ap- 

 plications do not reach the lower surface, hence a spray is 

 preferable. The larger loopers eat through the leaves, but when 

 they find anything distasteful they cease feeding and search for 

 tissue that has not been poisoned. After rainfall eggs hatch 

 and the poison having been washed away the larvae continue 

 feeding. Sirrine obtains good results with resin-lime mixture. It 

 requires about two hours to make this mixture, and considerable 



Fig. 94.— Cabbage boper carasitized by Copidosoma 'runcakUa Slightly enlarged 

 (After Riley, U. S. Dept. Agr J 



care is necessary in its preparation; but when crops are grown 

 on a large scale it might pay to use this remedy. It has the 

 advantage of being more adhesive than a Paris green spray, 

 remaining on the under surfaces as well as upper leaves and 

 requiring two or three heavy rains to remove all of it, even on 

 the exposed portions of leaves. Arsenate of lead has similai 

 adhesiveness, and as it has given good results in experiments 

 on a small scale it should receive further tests. 



The Imported Cabbage Webworm (Hellula undalis Fab.). — 

 As if the cabbage-grower did- not have enough "worms" with 

 which to contend a new species has recently appeared in the 

 South, and there is now the threatened danger of its introduc- 

 tion farther north in the same manner as has happened in the 



