50 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 
The cocoon (fig. 14) is elliptical, whitish (except in the case of the winter- 
ing pupe), 1 mm. in length by 0.55 mm. wide, and is spun on the under- 
side of the leaf in the protecting angles of the midveins, etc. (fig. 14). 
In selecting a site for the cocoon the larva incloses within the pre- 
liminary fibrils two or three mite eggs, presumably for nourishment 
while spinning the cocoon. A larva was seen to attach a fibril deftly 
to the dorsal bristles of an adult female that happened to wander in 
among the guy-fibrils of the cocoon. ‘‘Staked out’’ in this manner 
the female remained 
tethered long enough 
to deposit two eggs 
in the precise position 
suitable to the con- 
ta:8 venience of the spin- 
ninglarva. No effort 
* is made, apparently, 
to conceal the sum- 
mer cocoons, but the 
overwintering co- 
coons are designed 
with the idea of con- 
cealment. Specimens 
of the latter type are 
very inconspicuous, 
owing to the fact that 
they assume almost 
the exact color shade 
of the surface upon 
which they are con- 
structed. 
Res : Assuming the incu- 
Fig. 14.—Cocoon of Arthrocnodaz carolina on underside of violet leaf. : ; 
(Drawn by camera lucida.) (Original.) bation period to be 
about 3 days (as is the 
case with certain similar forms), with 5 days for the larval stage and 
8 days for the pupa, the entire cycle from deposition to the issuance 
of the adult midge will be approximately 16 days. We are inclined 
to believe that under optimum conditions the cycle may be com- 
pleted in somewhat less time than this. Table XX presents the 
records of predation which we have secured. 
a 
