106 INSECTS AFFECTING DOMESTIC ANIMALS. 
He reared the fly from which his description is made from a larva 
obtained from the striped squirrel or chipmunk (Tamias striatus lysteri). 
The larva occurred in the scrotum, causing it to become unnaturally 
enlarged, and when found lay with tail end next a small opening 
‘“Jarger than the head of a large pin, the testicles being entirely con- 
sumed.” This larva buried itself August 13, 1856, and issued as fly 
July 29, 1857. So far as we know, this is the only adult of the species 
which has ever been reared. 
Some notes upon the species were published by Riley and Howard 
in Insect Life (Vol. I, p. 214), with figures of the larva, a few paragraphs 
of which we reproduce here, with the figures. 
Fie. 49.—Cuterebra emasculator: a, full-grown larva from above; b, same, from below—enlarged; ec, 
head of same; d, anal end of same; ¢, portion of integument of same—still more enlarged (from 
Insect Life). 
Dr. Fitch published a painstaking description of the different stages and gave the 
species the name of Cuterebra emasculator from the larval habit which he supposed 
characteristic. He mentions the fact that hunters in the vicinity of Lakeville, N. Y., 
where the first specimen sent him was found, had long been familiar with the fact 
that at least one-half of the male gray squirrels shot in that vicinity were found to 
be castrated, and that it was the opinion of hunters that the deformity was caused 
by the squirrels seizing and biting out the testicles of their comrades. In support 
of this idea he gives the testimony of Mr. Hurst, taxidermist of the New York State 
Cabinet of Natural History, who ciaimed to have seen a half dozen red squirrels 
unite in mastering a gray one and castrating him. Dr. Fitch queries whether the 
bot-fly may not be attracted by the wounds so made, if this habit prove common, 
but concludes that the object of the joint attack of several upon one is rather to 
kill the grub which is engaged in emasculating him, 
we 
. . 
