112 ENTOMOLOGICAL NEWS. [April, 



On another occasion the writer happened to spy the Asilus just 

 finishing a wasp, and though its body was somewhat larger than 

 the robber the latter flew off with it almost as swiftly as if not at 

 all burdened. One frequently comes across our common Asilus 

 struggling in the grass with a moth, sometimes twice the size of 

 the fly, and it is not uncommon to find him with a bumble-bee,' 

 which he will carry from grass-stalk to grass-stalk when disturbed. 

 A light brown Asilus, rather rare about Philadelphia, occasionally 

 seizes upon the common sulphur-yellow field butterfly, Colias 

 philodice. 



The keen sword -like proboscis of the robber fly is easily thrust 

 through the hard coat-of-mail of a wasp, hornet, certain beetles 

 and all other softer insects, and will stop their struggles in a few 

 seconds. But the robber occasionally attacks insects that pos- 

 sess such invulnerable outer crusts that hjs sharp bill cannot 

 pierce it. A friend tells of an instance in which he saw a robber 

 fly attack a gold bee, Ckrysis, a small metallic-colored insect that 

 is so hard that one cannot crush it between the finger and thumb. 

 The fly held the bee easily enough, despite its struggles, but 

 could not thrust his proboscis into the head or thorax of the 

 Chrysis, and afi:er repeated trials gave up the job and flew away, 

 and the bee, not hurt at all, flew away also. 



The writer once saw a robber fly drop a divaricated Buprestis 

 (the pretty beetle, golden and green, that boys call "coat-tails") 

 and the beetle ran away unhurt. The robber had evidently been 

 trying to thrust its bill through its hard exterior and had failed. 

 There are several beetles that will thus foil the Asilus. 



The Asilus also sometimes more than meets his match. I once 

 witnessed an affair between a large black robber fly (found only 

 in the South and when on the wing, in general appearance, like 

 a dragon fly) and the famous sand hornet, the beautiful Stigus. 

 The hornet is another rapacious insect, but uses the paralyzed 

 bodies of her victims only to lay her eggs in, then'burying tiiem, 

 that the coming generation of hornets, when hatched, will have 

 food and shelter with which and wherein to carry on their trans- 

 formations into the full-grown insect. The victims of the Stigus 

 are fat grasshoppers or spiders and the dog-day locust, Cicada 

 pncinosa, a first cousin to the seventeen-year locust of fame. The 

 struggle between the hornet and her victim is over more quickly 

 than that between the Asilus and his prey. The Cicada is very 

 swift of wing, and I do not believe the robber fly could catch it, 

 but the hornet often does catch and kill it in the air. 



% 



