614 AN INTRODUCTION TO ENTOMOLOGY 



The evergreen bag-worm or the bag-worm, Thyridopteryx ephe- 

 mercBJormis. — This species prefers red cedar and arbor-vitae, and for 

 this reason has been named the evergreen bag-worm; but it also 

 feeds on many other kinds of trees, and as it is the species that is 

 mosthkelyto attract attention, and is sometimes a serious pest, it is 

 often called the bag-worm. It is our best-known species, and iis 

 life-history will serve as an illustration of the habits of the members 

 of the family Psychidas. 



The bag of this species is about the same size as that of Abbot's 

 bag-worm (Fig. 748); but it differs in being covered with bits of 

 leaves when it feeds on cedar or arbor-vitse, or with twigs attached 

 lengthwise when it feeds on other trees. When full-grown the larva 

 fastens the bag to a twig with a band of silk, and then changes to a 

 pupa. When the male is ready to emerge, the pupa works its way 

 to the lower end of the bag and halfway out 

 of the opening at the extremity. Then its skin 

 bursts and the adult emerges. The male moth 

 has a black, hairy body and nearly naked wings 

 (Fig. 750). The adult female partly emerges from 

 the pupa skin and pushes her way to the lower 

 end of the bag, where she awaits the approach of 

 Fig. 750.— Thyridop- the male. She is entirely destitute of wings and 

 \orZl '^^''^"'''' legs. The genitalia_ of the male can be 

 greatly extended, making possible the pairing 

 while the female is still in the bag. After pairing, the female works 

 her way back into the pupa skin, where she deposits her eggs mixed 

 with the hair-like scales from the end of her body. She then works 

 her shrunken body out of the bag, drops to the ground, and perishes. 

 The eggs remain in the pupa skin in the sac till the following spring. 



Where this insect is a pest, two methods of control are practiced, 

 first, the bags are collected and destroyed in the winter, while they 

 still contain the eggs; second, when impracticable to collect the bags: 

 on account of the height of the infested trees, a spray of arsenate of 

 lead is used in the spring as soon as possible after the larvee appear. 



Eurycyttarus confederdta. — This is a 



smaller species than the two preceding 



ones. Figure 751 represents the sac of a 



male with the empty pupa-skin projecting 



from the lower end, and Figure 752 the 



fully developed male. Fig. 752. 



Solenobia walshella. — This is a small 

 Fig. 751. tineid-like species; the male has a wing-expanse of about 13 



mm. and the hind wings have a quite wide fringe. The fore 

 wings are light gray speckled with brown. The bag of the larva 

 is about 8 mm. long, made of silk, and covered with fine grains of 

 sand or with particles of lichens and excrement of the larva. Cham- 

 bers states that he has sometimes found small molluscan shells ad- 

 hering to it. The larvse are found on the trunks of trees and feed 



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