ON AN 
INSECT OF THE FAMILY JCHNEUMONIDZ 
WHOSE LARVA IS PARASITIC ON SPIDERS. 
—_~>——_ 
Immature Spiders of the species Epeira antriada, 
Lpeira inclinata, Epeira cucurbitina, and Epeira dia- 
dema, and adults of the species Linyphia minuta and 
Linyphia tenuis, are frequently infested by the larva 
of the Polysphincta carbonaria of Gravenhorst, which 
feeds upon their fluids and ultimately occasions their 
death. ‘This parasite is always attached to the upper 
part of the abdomen, near its union with the cephalo- 
thorax, generally in a transverse but occasionally in a 
longitudinal direction ; and, though it proves a source 
of constant irritation, is secured by its position from 
every attempt of the spider to displace it. Being 
apodous, it appears to retain its hold upon its victim 
solely by the instrumentality of the mouth and of a 
viscid secretion emitted from its caudal extremity. I 
never saw more than a single larva on the same 
individual spider, which, indeed, could not supply 
sufficient nourishment for two. 
In the earlier stages of its growth this parasite has 
