184 GEO. D. HULST. 



Egg. — White, faintly glossy; oval iu outline, i mm. long, i mm. wide; surface 

 closely indented with large, irregular, five- or six-sided pits; the walls of the 

 indentations forming sharp ridges over the surface of the egg. 



Nkwly hatched larva. — Length 5 mm. Color dull white, tinged with yel- 

 low ; head and thoracic shield dark hrown ; mouth parts dull yellow ; body at- 

 tenuated ; head and thoracic plate large, round, flattened dorso-ventrally ; head 

 with several long lateral hairs; each abdominal segment furnished laterally with 

 a long stiflf hair ; thoracic and prolegs strong and well developed. 



Chrysalis. — Length 6.5 mm. Color: dorsum dark brown, inclining to black- 

 ish toward anus, venter a little lighter, wing and antenual sheaths yellowish 

 brown. Wing sheaths reaching nearly to the sixth abdominal segment; antennal 

 sheaths reaching to the tip of the wing sheaths ; dorsum densely punctured, 

 venter less so; stigmata at the tips of slight protuberances; tip of abdomen 

 nearly surrounded by a whorl (complete dorsally, incomplete ventrally) of small 

 pointed tubercles. 



Prof. Comstock, in addition, gives the following history of this 

 insect: " While studying a colony of the cottony ma})le scale (Pid- 

 vinaria inrnimerabilis) which was found on a branch of Negnndo 

 aceroides in Washington, I was surprised to find a Pyralid larva 

 living within the cottony mass excreted by these insects. On further 

 examination it was found that very many of the bark lice afforded 

 retreats for similar larvre. This, with the fact that the eggs deposited 

 by such individuals or the young lice developed from them, had been 

 destroyed, indicated that the Pyralid larvse were predaceous. One 

 of these larvae was placed in a glass tube with a bark louse, the eggs 

 of which had not been destroyed. These eggs had just hatched, and 

 the cottony excretion was swarming with the young lice. The larva 

 soon made its way under this mass, and after spinning a delicate 

 silken tube about its body began to devour the young lice greedily. 



Although the caterpillar is well protected, living, as it does, within 

 the mass of cottony excretion, it spins about its body a delicate silken 

 tube, which when spun within the cottony mass is with difficulty 

 distinguished from it. When a branch is thickly infested by Pul- 

 vinaria, these tubes extend from one bark louse to another. The 

 caterpillars are very active, moving about freely within these silken 

 passages from beneath one scale to another. 



At the time my observations were made (June '24th) many of the 

 caterpillars were full grown, and some of them transformed at once. 

 The cocoon is made within the silken tunnel and is quite delicate, 

 the pupa being plainly visible within it. Individuals of this brood 

 remained ten days in the pupa state. The greater number bred by 

 me issued July 17th ; some, however, did not appear until Aug. 13th. 



