THE BAG-WORM. 23 
worm, and they serve not only as a protection to 1t, but also to the 
eggs. Upon cutting open the larger of these bags in winter time they 
will be found to contain the shell of a chrysalis (technically called the 
puparium), which is filled with numerous small yellow eggs (Fig. 7 e). 
Each of these is a little over 1 millimeter in length, obovate in form, 
and surrounded by a delicate, fawn-colored, silky down. In this con- 
dition the eggs remain from fall throughout the winter and early 
spring. 
Fic. 7.—Thyridopteryx ephemereformis: a, larva; b, male chrysalis; ¢, female moth; d, male moth; 
¢. follicle and puparium cut open to show eggs; f, full grown larva with bag; g, young larve with 
- their conical upright coverings; all natural size. 
The Larva and its Bag.—About the middle of May in this latitude the 
eggs hatch into small but active larvae, which at once commence to con- 
struct a portable case or bag in which to live. ‘The way in which this bag 
is prepared is curious (Fig. 8). The young larva crawls on a leaf and, 
Fic. 8.—Thyridopteryx ephemereformis. How the young larva prepares its bag. 
gnawing little bits from the surface, fastens these together with fine silk 
spun from its mouth. Continually adding to the mass, the larva finally 
