1 894.] ENTOMOLOGICAL NEWS. Ill 



istics. The order possesses the fastest rivers, the biggest eaters, 

 the strongest jumpers (the flea), the most gluttonous blood- 

 suckers and the most rapacious species of the class insecta. Of 

 the rapacious Diptera, the typical example is the robber tly, 

 known to naturalists by the scientific term Asi/us, of which there 

 are many different species, large and small. Our most common 

 species around Philadelphia is about one inch long, light and 

 dark brown, with silky, gray tufts of hair about its body and a 

 bluish spot at the last segment of its slender abdomen. 



The robber fly is the peregrin falcon of insects, and hawk fly 

 would be a better name for it. It will seize almost any insect as 



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its prey, often a grasshopper so large that it cannot fly with it or 

 a stout moth, sometimes many times larger than itself, a bug, 

 beetle, fly, or even a bee, wasp, or small hornet. The Asilns 

 seems rather inclined toward the stinging Hymenoptera (the bee 

 and wasp order), and there is a species found in the Southern 

 States that makes the annulated paper nest wasp Polistes almost 

 exclusively his prey. The robber fly has three principal charac- 

 teristics that serve his hawk-like habits: long, but strong legs, a 

 long and exceedingly sharp, sword-like proboscis, and muscular 

 wings that enable him to overtake almost every other insect in 

 the air or to pounce upon his victim resting on leaf or flower. 

 If he seizes a bee or wasp his legs are long enough to hold his 

 prey so that he cannot be reached by the sting. His proboscis, 

 held when inactive in a sort of double sheath, the point just pro- 

 truding, is capable of great extension, and is also a haustelum; 

 with it the Asilus sucks the juices of his victims. No insect will 

 live any length of time with a considerable part of its insides 

 pumped out. The robber fly always pounces upon the back of 

 a wasp or other insect; sometimes when its prey is apparently 

 unsuspecting. The struggle is short, sharp and decisive. An 

 Asilns has been seen to seize a grasshopper, and the powerful 

 Arridian did everything, lor a few moments, to dislodge its 

 raptor, the first few springs rolling them both over in the grass, 

 the robber keeping his hold and remaining on the grasshopper's 

 back, while the latter tried to scrape the fly off with his Ion- 

 hind legs. In a moment the sword proboscis was thrust away 

 into the back of the 'hopper's head, and with a few convulsive 

 kicks the Acridian expired, literally bereft of his brains, or what 

 part of them the fly could make a meal of. 



