26 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
size and transparent wings, is rarely observed in nature. The life-dura- 
tion of this sex is also very short. The female imago is naked (save a 
ring of pubescence near the end of the body of yellowish-white color), 
and entirely destitute of legs and wings (Fig. 7, ¢, and Fig. 9, b). She 
pushes her way partly out of the chrysalis, her head reaching to the 
lower end of the bag, where, without leaving the same, she awaits the 
approach of the male. The manner in which the chrysalis shell is elon- 
gated and reaches to the end of the bag is shown in Fig. 9, a, and an 
enlarged side view of the female showing the details of structure 
shown at b, in the same figure. The extensility of the male genitalia, 
which permits him to reach the female within her bag, is set forth in 
the accompanying Fig. 10, where the parts are shown at rest, ¢ and d, 
Fic. 10.—Thyridopteryx ephemereformis : b, The 
end of male abdomen from the side, showing gen- 
italia extended; c, genitalia in 1epose ventral 
view ; d, do., dorsal viewenlarged. — 
and in action, b. Fertilizavion being accomplished, the female works 
her way back within the chrysalis skin and fills it with eggs, receding 
as she does so toward the lower end of the bag, where, having completed 
the work of oviposition, she forces, with a last effort, her shrunken body 
out of the opening, drops exhausted te the ground, and perishes. When 
the female has withdrawn the slit at the head of the puparium and the 
elastic opening of the bag close again, and the eggs thus remain securely 
protected till they are ready to hatch the ensuing spring. 
GEOGRAPHICAL DISTRIBUTION. 
The Bag-worm occurs most frequeutly in the more southern portion 
of the Middle States and in the Southern States, but seems to be absent 
from the Peninsula of Florida. Within these limits it extends from the 
Atlantic to Texas, and reaches the less timbered region west oi the 
