290 



MOTIONS OF INSECTS. 



wings, if it does not fly like a hawk, is so rapid as not to be 

 perceptible. When the crane-fly ( Tipula oleracea) is upon 

 the wing, its fore-legs are placed horizontally, pointing 

 forwards, and the four hind ones stretched out in an opposite 

 direction, the one forming the prow and the other the stern 

 of the vessel, in its voyage through the ocean of air. The 

 legs of another insect of this tribe (Hirtcea Marci) all point 

 towards the anus in flight, the long anterior pair forming an 

 acute angle with the body : — thus, perhaps, it can better cut 

 the air. 



I have often been amused in my walks with the motions 

 of the hornet-fly (Asilus crabroniformis), belonging to the 

 second division just mentioned. This insect is carnivorous, 

 living upon small flies. When you are taking your rambles, 

 you may often observe it alight just before you ; as soon as 

 you come up, it flies a little further, and will thus be your 

 avant-courier for the whole length of a long field. This 

 usually takes place, I seem to have observed, when a path 

 lies under a hedge ; and perhaps the object of this manoeuvre 

 may be the capture of prey. Your motions may drive a 

 number of insects before you, and so be instrumental in 

 supplying it with a meal. Other species of the genus have 

 the same habit. 



The aerial progress of the fly tribes, including the gad-flies 

 (GEstridce), horse-flies (Tabanidce), carrion-flies (Muscida), 

 and many other genera — which constitute the heavy horse 

 amongst our two-winged fliers — is wonderfully rapid, and 

 usually in a direct line. An GEstrus about to attack a horse 

 urged to its full speed will yet keep close to it, and, at last, 

 when foiled in its object, fly away before it at a still more 

 rapid rate. 1 The male Tabani, according to the observations 

 of M. de St. Fargeau, when met with in the long avenues of 

 the continental forests, are seen to dart impetuously from one 

 end to the other, then to rest a while immoveable, suspended 

 in the air, and look around on every side, and again to rush 

 with equal velocity to the other end, repeating these 

 manoeuvres till they have discovered a female, upon which 



1 Burmeister, Manual of Ent. AG?,. 



