126 NEW VOKK STATE MUSEUM 



complete somersault and lies on its back, held down by the band fh^^ 17 rj. 

 By a (jiiick turning movement the larva regains its feet, the band now 

 extending across its neck | fig. i 7 (/J. It then adds to the band at each end 

 till the two ends meet, and they are then fastened together so as to form a 

 kind of narrow collar which encircles the neck of the worm. P'ar from 

 resting, it now busies itself by adding row after row to the anterior or lower 

 end of the collar, which thus rapidly grows in girth and is pushed further 

 and further over the maker [fig. 17 t']. The inside of this bag is now care- 

 fully lined with an additional layer of silk, and the larva now marches off, 

 carrying the bag in an u])right position. 



The case is carried in an upright position for a time but as it becomes 

 heavier it is allowed to hang down | pi. 8, fig. 17]. Holes are eaten out of 

 the leaves | pi. 8, fig. 15] as the larvae increase in size and [)ieces therefrom 

 are attached to their protective covering. The cases are enlarged from 

 time to time to nicest the requirements of the growing caterpillar. The 

 peculiar, ragged appearance produced by half grown bag worms is shown 

 on the leaf just below figure 22, plate 8. The caterpillars attain their full 

 size in July or August and in early September they become restless and 

 wander to other trees and shruljs. Next the bags are securely fastened to 

 twigs (sometimes the males attach their bags to leaves) by broad bands of 

 silk I pi. 8, fig. 10], and the caterpillars then transform to pupae and about 

 three weeks later assume the adult form. The males are on the wing 

 during .September and October. Their a]i])earance is preceded by the male 

 pupa wriggling itself partly out of the larval case, thus permitting the occu- 

 pant to escape direct from his ])upal case to the free air \sri' pi. 8, fig. 22]. 

 The female does not leave hers till after ovipositing but works out of her 

 case far enough to permit pairing, returns, oviposits and then escapes from 

 the case ami di(-s. The posterior portion of the jnipal shell, which is the 

 upper part as it hangs, is filled with eggs, and the anterior or lower part 

 with the yellowish downy substance which is also intermixed with the eggs 

 to some extent. The eggs may be found tlie latter part of October and 

 the winter is passed in this form, as previously stated. 



Food plants. This caterpillar feeds on a number .of trees and shrubs. 

 It is most injurious to evergreens on account of their not withstanding 



