842 [Assembly 
gin of fore wings blackish. Length about 0.07. Hatched from an nndescribed aphis 
infesting the base of the leaves of the Balm of Gilead (Populus candicans). 
But without dwelling longer upon this interesting group of in¬ 
sects which render us such important services, we close with a 
notice of a species which destroys the aphis of the garden cherry, 
and which differs from all the foregoing in its residence when in 
the pupa state. As if fearful that the beak and feet of the dead 
aphis would not hold its svvoolen body securely to the smooth 
surface of the cherry leaf, the worm of this species when ready to 
enter its pupa state perforates the abdomen of the aphis upon its 
under side, probably as soon as its life is extinct, and spins a 
cocoon for itself between the leaf and the body of the aphis, the 
leaf forming the floor of the room for its residence, the abdomen 
of the aphis forming its roof, and a gray paper-like membrane 
which it weaves constituting the sides and attaching the body of 
the aphis securely to the leaf. The walls of its domicil are so 
thin that the inclosed pupa can sometimes be seen faintly through 
them, of a bright yellow color. 
The Cherry Aphidius (Trioxys Cerasaphis ) is black with its palpi or feelers and 
legs pale yellowish brown; antenna; almost as long as the body, 18-jointed, the third 
and following joints equal, cylindric, thrice as long as broad, the last elongated 
ovate; abdomen elliptic, rather narrower and shorter than the thorax, scarcely pedi- 
celled at its base, shining, tinged with brownish; wings pellucid, stigma smoky white. 
Length 0.07. 
