NATURAL ENEMIES OF THE LOCUST. 
265 
"au milieu des d6blais, oil gisaient par-ci par-la des coques de Colletes" (Ann. Soc. 
Ent. France, 3d ser., torn, vi, p. 505, pi. 13, Fig. Ill, and details). The larva is elon- 
gated, apod and fleshy, and of a white color. The preceding observations clearly prove 
that the larvae of the Bonibylii are parasites in the nests of other insects, in the manner 
of the cuckoo among birds. 
The last statement of Professor Westwood is, however, not justified 
by Dufour's observations. On the contrary, Dufour expressly states 
that he did not observe upon what the larva fed ; the inference which 
he draws is based upon the analogy of Anthrax, 334 and he inferred that it 
was upon the larvae of Colletes that the grub fed ; quite a different thing 
from being a cuckoo in the nest and feeding only upon the pollen. 
There is, in Dufour's paper, no evidence to prove that the Bombylius 
larva was found in the cocoons, or even in the cells of the bee; he 
states, in fact, that he failed to find it there, but found it among the 
clearings (deblais) which he had made in digging out the nests. Prof. 
"Westwood himself found numbers of Bombylius medius flying in asso- 
ciation with a species of Andrena in the unpaved Forum Triangulare of 
Pompeii, and found at the same spot the pupa-shell of the fly protudiug 
from the ground. 
Dr. Packard (" Guide," &c, p. 397) states that ■" a species [of Bomby- 
lius] is known in England to lay its eggs at the opening of the holes of 
Andrena, whose larvae and pupae are devoured by the larvae of the fly." 
But no authority is given for the statement. 
Messrs. Allen and Underbill, in Science Gossip, 1875, p. 80, express 
their belief that the Bonibylii are parasitic on humble-bees. In the 
volume for 1876, p. 171, they say (speaking of Sitaris) : 
In relation to the larva of this beetle, we would remark that this year we have found 
it clinging to Bombylii. This is " circumstantial evidence " that Bombylii frequent the 
nests of Anthophora to lay their eggs, since Sitaris itself, from its manner of life, can- 
not be the parasite of a fly, but only of a bee. 
Locust eggs might well have been in the spots where Lucas, Dufour, 
and Westwood found the Bombylius. 
From all these notes, it is clear that the true habit of BombyUid larvae 
had not been clearly ascertained. That they preyed parasitically on 
nest-building Hymenoptera was rendered probable by what was known 
of the parasitism of the allied Anthracids; but we had only assump- 
tion without proof, and the experience we now record weakens the force 
of the assumption. 
In his "Western Diptera" (1. c. p. 243) Baron Osten Sacken gives 
references to the published account of the parasitism of the Anthracid 
genus Argyramccba within the nests of Cemonus and Chalicidoma, cites 
Z '"I% has been clearly ascertained, and is well known that Anthrax feeds in the larval 
state upon the young of certain bees. The larva of the Anthrax before attaining its 
own full growth and before destroying its host must await the full growth of the 
latter, as it has, by several observers, been bred from the cocoons of the insects upon 
which it was parasitic. 
