28z 



THE AMERICAN ENTOMOLOGIST. 



to Trypoxvlon. We have similar cells 

 from Texas and other parts of the South. 

 They differ from those of Pelopirtis in 

 being wider, ribbed on the upper surface 

 and fastened not only side by side but in 

 long tubes end to end. The Pelopmtis 

 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 darkened and docked ; 

 the Trxpoxyloii spins a tougher, thicker, 

 more solid and smooth cocoon of a dull, 

 bark-brown color, generally about half as 

 long as the other ;but varying greatly 

 in size) and with the head-end often ex- 

 panding into a flange. 



We have reared what is very near, and 

 probably identical with, ArgyraniKba fur 

 from larvre that had preyed on Trypoxylon 

 albitarsc which had made use of the mud 

 cells oi Pclnpiviis /iiiiatus, or the Common 

 Mud-dab, in Texas ; also from the same 

 was]) that had made use of the burrows 

 of a bee [Anthophora abriipta Say). 



'I'lie larva of Argyniiiuvha has very 

 mu( h the same appearance as that of 

 Svsta'chus and Triodites, and the pupa is 

 distinguished from the pupa of this last 

 principally by its longer and more numer- 

 ous hairs, longer anal spines and more 

 conspicuous spiracles. 



The discovery of the " parasitism " of 

 these Bee-flies upon locust-eggs at once 

 suggests a comparison with the similar di- 

 versity of parasitic habits among the Mc- 

 loiila as given in our First Report, some of 

 them infesting l)ee-cells, while others, as 

 the true Blister-beetles iLyt/iiii) feed on 

 locust eggs. 



The Anthracids are now united by the 

 best authorities witli the Bombyllida;, of 

 whii'h family as a whole, Osten Sacken 

 has said;t they are "perhaps the most char- 

 acteristic and one of the most abundantly 

 represented families of Diptcra in the 

 western region, imluding California." The 

 abundance of Blister-beetles is also well 

 known to i haracterize this region, and we 

 have shown how this abundance is con- 

 nected 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 char- 

 acterization of the fauna in these two 

 groups is really dependent upon the pres- 

 ence of the Locusts as well as upon the 

 rich representation of the burrowing Hy- 

 menoptera. 



With these general remarks we will now 

 give a more full and descriptive account 

 of the two Bee-flies which, by rearing from 

 the larva, we know to have this locust-egg- 

 feeding habit. 



SVSTiECHUS ()RF,.\S. 



The character of the eggs and the man- 

 ner in which they are laid have not yet been 

 observed. The larx'afFig. 147,(7) has already 

 been described in our First Report (p. 305^ 

 and is found in the locust egg-pods or 

 near them, of different sizes, during most 

 of the year. These larvae begin to trans- 

 form to the pupa state early in the sum- 

 mer, and the pupa (Fig. 148) pushes itself 

 half-way out of the ground in order to dis- 

 close the fly. These flies continue to issue 

 during the summer months. As a rule but 

 one year is required for full development, 

 but there is in this respect great irregularity, 

 and the same tendency to retardation 

 which we have called attention to in the 

 case of the Blister-beetles. We have had 

 quite a number of the larvK remain over 

 unchanged till the second year, and all 

 that we have said as to the philosophy 

 of this retardation in the one case applies 

 in the other. We are inclined to think 

 that future observations will show, that 

 there is a still further parallel in that the 

 newly-hatched larvre of the Bee-flies are 

 much more active than in the later stages, 

 and somewhat different in structure. 



The three later states of the insect maj' 

 be characterized as follows :, 



[We omit the more detailed descriptive 

 parts of the article. With additional ma- 

 terial we have been enabled to examine 

 more full) the structure of the head than 

 we had in giving the original description.* 

 Underneath the median elevated piece. 



t L. c, p. 22B, 



*Niiuh Mo. Ent. Rpt., p. 96, 



