26 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



and the imago appears as a winged moth with a black, hairy body and 



glassy wings (Fig. 7 d). It is swift of flight, and, owing to its smalt 



size and transparent wings, is rarely ob- 

 served in nature. The life-duration of 

 this sex is also very short. The female 

 imago is naked (save a ring of pubes- 

 cence near the end of the body of yel- 

 lowish-white color), and entirely desti- 

 tute of legs aud wiugs (Fig. 7 c, and 

 Fig. 9 b). She pushes her way partly 

 out of the chrysalis, her head reaching- 

 to the lower end of the bag, where, with- 

 out leaving the same, she awaits the 

 approach of the male. The manner in 

 which the chrysalis shell is elongated 

 and reaches to the end of the bag is 

 shown in Fig. 9 <r, and an enlarged side 

 view of the female 1 , showing the details 

 of structure, is shown at Z>, in the same 

 figure. The extensility of the male gen* 

 italia, 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, c and tf, and 



in action, b. Fertilization 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 



to 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the female has withdrawn the slit 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 se- 

 curely protected till they are ready 



to hatch the ensuing spring. 



FiG. 9.—Thyridopteryx ephemercpformis: 

 a. Follicle out open to show the manner in 

 which thefemaleworksfroraherpuparium 

 and reaches the end of the bag, natural 

 size; b. female extracted from her case, 

 enlarged. 



GEOGRAPHICAL DISTRIBUTION. 



FlG. 10. — Ihyridopteryxephemerceformis: &, The 

 end of male ahdomen from the side, showing gen- 

 italia extended; c, genitalia in repose ventiat 

 view; d, do , dorsal view enlarged. 



The Bag- worm occurs most fre- 

 quently in the more southern por- 

 tion of the Middle States aud in 

 the Southern States, but seems to be absent from the Peninsula of Flor- 

 ida. Within these limits it extends from the Atlantic to Texas, and 

 reaches the less-timbered region west of the Mississippi, ^Northward^ 



