266 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
Scliluer's statement that the larvae live parasitically in pupae of Lepidop- 
tera, and records the breeding of A. cephus and A. fur from the nest of 
a Texan mud-wasp, which he referred, with a question, to Pelopcem, but 
which, as we have ascertained from an examination of the mud tubes 
which are deposited in the Cambridge Museum of Comparative Zoology, 
belong to Trypoxylon. We have similar cells from Texas and other 
parts of the South. They differ from those of Pelopoeus, in being 
wider, ribbed on the upper surface, and fastened not only side by side 
but in long tubes end to end. The Pelopceus spins a thin, yielding, semi- 
transparent, elongate cocoon of a golden-brown color, with more or less 
loose silk around it and the tail end thickened and docked; the Try- 
poxylon spins a tougher, thicker, more solid, and smooth cocoon of a dull, 
dark brown color, generally about half as long as the other (but varying 
greatly in size), and with the head-end often expanding into a flange. 
We have reared what is very near to and probably identical w ith 
Argyramocba fur from larvae that had preyed on Trypoxylon albitarsc 
which had made use of the mud cells of Pelopceus lunatm, or the common 
mud-dab, iu Texas ; also from the same wasp that had made use of the 
burrows of a bee {Anthophora abrupta Say). The larva of Argyramceba 
has very much the same appearance as that of Systceclws and Triodites 
and the pupa is distinguished from the pupa of this last (PI. XVI, Figs. 
5, 5 a), principally by. its longer and more numerous hairs, longer anal 
spines, and more conspicuous spiracles. 
The discovery of the "parasitism" of these Bee-flies upon the locust 
eggs at once suggests a comparison with the similar diversity of para- 
sitic habits among the Melo'idce, as given in our First Eeport, some of them 
infesting Bee-cells, while others, as the true Blister-beetles (Lyttini) feed 
on locust eggs. 
The Anthracids are now united, by the best authorities, with the Bom- 
byliidcc, of which family as a whole Osten Sacken has said: 335 They are, 
"perhaps, the most characteristic and one of the most abundantly rep- 
resented families of Diptera in the western region, including California." 
The abundance of blister-beetles is also well known to characterize this 
region, and we have shown how this abundance is connected with the 
abundance of locusts. It is of interest, therefore, to find that the Bee-flies 
bear a similar relationship of parasitism to the latter, and that the 
characterization of the fauna in these two groups is really dependent 
upon the presence of the locusts as well as upon the rich representation 
of the burrowing Hymenoptera. 
With these general remarks we will now give a more full and descrip- 
tive account of the two bee-flies which, by rearing from the larva, we 
know to have this locust-egg-feeding habit. 
Xystcschus oreas. 
The character of the eggs and the manner in which they are laid have 
not yet been observed. The larva (PI. XVI, Fig. 1) has already been 
335 L. c, p. 225. 
