122 SECOND ANNUAL REPORT OF 



Fitch, of New York, from Mr. R. O. 

 Thompson of this State, who found that 

 it had the pernicious habit of catching 

 and sucking out the juices of the com- 

 mon honey-bee. Dr. Fitch referred this 

 fly to the genus Trupanea, and called 

 it the Nebraska bee-killer, from its 

 having first been captured by Mr. Thomp- 

 son in Nebraska, where he at that time 

 resided. The great German Dipterist, 

 H. Loew, as I am informed by Baron 

 Osten Sacken of New York, ignores and 

 has discontinued the genus Trupanea, substituting in its place that of 

 Promachus\ and Fitch's Trupanea apivora is the very same species 

 previously described by Loew as Promachus Bastardii, and it is one 

 of the most common species, occurring very generally over the United 

 States. 



I find that we have in Missouri a somewhat larger fly (Fig. 89) 

 which has the same pernicious habit of seizing and destroying the 

 honey-bee in preference to all other kinds of prey. It acts in exactly 

 the same manner as the Nebraska Bee-killer, being, if anything, more 

 inhuman and savage. It belongs to the typical genus Asilus, and I 

 have called it the Missouri Bee killer (Asilus Missouriensis). Though 

 bearing a casual resemblance to the Nebraska Bee-killer, it may very 

 readily be distinguished from that species, and especially by the dif- 

 ferent venation of the wings. 



[ Fi s- 90.] The three more common genera of these vora- 



cious Asilus flies, may easily be distinguished 

 from each other by the character of these wing- 

 nerves. In the typical genus Asilus to which 

 belongs our Missouri Bee- killer, the third longitu- 

 dinal vein is forked near the terminal third of the 

 wing, and the vein itself is connected about the 

 middle of the wing, with the fourth longitudinal, as 

 in Figure 90, b. In the genus Promachus* to which 

 the Nebraska Bee-killer belongs, it is the second 

 (not the third) longitudinal vein which is forked near the middle of 

 the wing, and the third branch of this fork is connected by a slender 

 oross-vein to the third longitudinal, near the terminal third of the wing, 

 as in Figure 90, a. In the genus Erax, which generally comprises 

 smaller species, the venation is similar to that of Asilus, but the 

 upper branch of the fork, instead of joining the third longitudinal 

 vein, is abruptly broken off and connected only near its termination 

 by a transverse vein, as in Figure 90, c. 



Asn.us Missouiuensis N. Sp. — Alar expanse 1. So; length of body 1.30 inches. Wings trans- 

 parent, with a smoky yellow tinge, more distinct around the veins, which are brown. Head pale 

 yellow, sometimes brownish ; moustache straw-yellow with a few stiff black hairs below; beard 

 pale straw-yellow ; crown very deeply excavated ; base of the same pale yellow with short, stiff* 



