THE CABBAGE PLUSIA: HABITS AND REMEDIES. 93 



Cannibalistic Habits. 



An instance has been given by a correspondent of the American 

 Entomologist, where this -species manifested a cannibaHstic propensity. 

 Two of the caterpillars having been inclosed in a box with two of those 

 of the cabbage butterfly, Pieris raj^CB, and three of another cabbage 

 pest, Piofiea rimosalis, upon opening the box three days thereafter, it 

 was found that the Plusias had killed and eaten all the others. Should 

 this love for its kind develop into a habit as strong as that existing in 

 the corn-worm, Heliothis armiger (^see First Report, pages 1 19-120), it 

 might become serviceable in reducing the number of its associate dep- 

 redators on the cabbage. 



Remedies. 



When not extraordinarily abundant, this insect may be kept in check 

 by a moderate amount of labor expended in hand-picking ; for as 

 the caterpillars usually rest with their body looped in m-shape, they 

 are conspicuous objects, and may be readily discovered and gathered. 

 They may also be destroyed by sprinkling the plants with hot water, of 

 a temperature not exceeding 150° Fahr., if applied through the nozzle 

 of a common sprinkler ; but if distributed in the finer spray of the rose 

 of a force-pump, a temperature as high as 170° should not injure the 

 leaves. But probably the best application, the easiest and the most sat- 

 isfactory, would be that of pyrethrum. A tablespoonful of good fresli 

 powder, diffused through two gallons of water and sprinkled over the 

 plants, would destroy the larvce — the more quickly if employed while 

 they are still immature. 



A preventive measure that would amply repay the effort would be to 

 capture the moths when they are abundant, in a net, as they hover 

 about the plants at dusk in readiness for the deposit of their eggs. 

 That they are so abundant at times as to be easily captured in this man- 

 ner is evident from the statement made by a gentleman from the Dis- 

 trict of Columbia, in commending this method, that in a long-continued 

 drouth '' the moths came in swarms, and afterward come the worms." 

 Catching the moths in their peculiar flight could easily be made a pleas- 

 ant pastime for the children of a family, while it might serve the addi- 

 tional purpose of leading them to the fascinating study of the habits of 

 the insect world. So simple a thing as an insect net, might thus, under 

 proper direction, become one of the most important of household im- 

 plements. 



