187 



fly escaped, however, the species is not known. Another was found 

 astride a grass stem (Sta. I, ^) with the stink-bug Bnschistus variola- 

 riiis grasped in its legs Aug. 12 (No. 39). Aug. 12, among the prairie 

 grasses (Sta. I, ^), a pair of these flies was taken copulating (No. 44). 

 Walsh (Am. Ent., Vol. I, pp. 140-141. 1869) states that Asilus preys 

 upon Polistes and Bonibus, which it grasps by the head-end, to keep 

 out of the reach of the sting, from the bodies of which it sucks the 

 juices. It handles a harmless grasshopper very differently. 



I have observed a large species of robber-fly at Havana, 111., which 

 hung suspended from grass while devouring its prey; and Aldrich 

 (Proc. Ent. Soc. Wash., Vol. 2, p. 147. 1893) observed a robber-fly 

 suspended by its fore feet, apparently asleep, holding a large beetle. 

 Cook (Bee-keepers' Guide, ninth ed., pp. 317-321. 1883) has seen a 

 species of robber-fly capture a tiger-beetle, Cicindela; many of these 

 flies furthermore prey upon the honey-bee. The introduction of this 

 bee into the prairie associciation must have had considerable influeiice 

 upon flower-frequenting insects, and especially upon the predaceous 

 kinds. 



The capture of the cabbage butterfly by an asilid is another obser- 

 vation which Cook has recorded for Proctacanthiis milbcrti Macq. 

 (Asilus niissouricjisis Riley). He says (1. c. p. 318) : "It has been ob- 

 served to kill cabbage butterflies by scores." Wallis (Can. Ent., Vol. 

 1-5' P- 135- 1913) observed this fly capturing Cicindela. Punnett 

 (Spolia Zeylanica, Vol. 7, pp. 13-15. 1910) has recently shown that in 

 Ceylon robber-flies are important enemies of large butterflies. Procta- 

 :anthus milbcrti has been observed to prey upon locusts (Riley, First 

 Q. S. Ent. Comm., p. 317. 1878). For an elaborate account of the 

 food and feeding habits of this family see Poulton, ('07). 



As very little is known of the l3reeding habits of the American 

 species, the observations of Hubbard on the oviposition of Mallophora 

 jrciiia Wied. (Second Rep. U. S. Ent. Comm., p. 262. 1880) are of 

 interest. He saw a female of this Florida species bury its abdomen in 

 the ground, where it deposited five or six eggs at a depth of half to 

 :wo thirds of an inch. The eggs hatched in a week. Brax lateralis 

 Macq. has been recorded as predaceous upon May-beetle larvae (Titus, 

 n Bull. 54, Bur. Ent., U. S. Dept. Agr., pp. 15-16). Titus gives fig- 

 ires of the larva and pupa. 



DOLICHOPODID^ 



^silopus sipJio Say. Metallic Milkweed Fly. (PI. XLVI, fig. 2.) 



This pretty metallic-colored fly, observed by almost every field 

 student or collector, is one of our commonest insects. It runs rapidly 



