464 SYNOPTIC COLLECTION. 



temperature is favorable, they will search for food, before 

 they are twenty-four hours old. 1 They feed chiefly at 

 night, going up the trees and out on the branches after 

 dark and returning to sheltered places before light. The 

 necessity of righting this insect intelligently and unceas- 

 ingly is evident when we consider that it is known to 

 destroy the foliage of nearly all trees and most plants of 

 economic importance. This is most unusual, for though 

 the newly hatched Lepidopterous larva is far less special- 

 ized in regard to its food plants than the mature larva, 

 yet the latter as a rule feeds upon a very restricted diet. 



The caterpillar when full grown becomes a pupa (No. 

 1176; PI. 1177, fig. 4) usually in July or August, and in 

 from eight to twelve days in Massachusetts the pupa 

 changes to the moth (Nos. 1176, 1178, <? ; PI. 1177, fig. 

 5; Nos. 1176, 1179, 9 ; PI. 1177, fig- 6). It is inter- 

 esting to notice the difference in size between the .well 

 fed specimens (Nos. 1178, 1179) and those less for- 

 tunate (No. 1176, specimens on the right). Within a few 

 hours after emerging from the pupa-case the female 

 lays eggs. The male is a swift flier, but the locomotion 

 of the female is limited to a few struggling flaps which 

 result simply in lessening the force of her fall from a 

 height. 2 She lays her eggs either before this fall or after- 

 ward and then dies. 



One of the moths that winter in the larval stage is 

 Pyrrhactia Isabella Smith (No. 1180. larva, pupa, cocoon, 

 imago), of the family Arctiidae. This is the black and 

 reddish brown colored caterpillar sometimes seen crawling 

 over snow. When the larva is ready to transform the 

 body shortens and apparently a thin gray veil slowly 

 covers it which grows thicker till the insect within is 



1 Rep. Mass. State Board Agric. on Work of Extermination of 

 Gypsy Moth, 1893, p. 12 (Senate document, No. 6). 



2 Howard, U. S. Dep. Agric., Div. Ent., Bull. no. u (n. s.), 1897, 

 p. 7. 



