THE CECIDOMYID^. 395 



living larvae within it (after Wagner). In the spring-time the little 

 perfect insect lays its eggs, and by-and-by the larvae are hatched 

 from them. If these larvae are examined, smaller ones will be 

 noticed inside them, and eventually they tear open the body of 

 their mother and escape. They reproduce others in the same 

 fashion, and a succession of these extraordinary generations takes 

 place during the whole of the fine weather. The increase of these 

 larvae progresses at a great ratio, and finally metamorphosis takes 

 place when the cold weather is at hand. This curious parthe- 

 nogenesis (from the larva, not from the perfect insect) has been 

 carefully studied by excellent observers, and is an established fact. 

 An equally interesting development from immature insects occurs 

 in the case of the larvae of Chironomus, which have been proved 

 by a Russian naturalist to contain eggs which are subsequently 

 laid by the pupae. The gall-making species are usually very small 

 as regards their individuals, and the females deposit their eggs in 

 the young shoots, leaves, or flowers, which they pierce by means 

 of their sharp-pointed ovipositor. Where this puncture is made a 

 gall or excrescence takes place, which grows sometimes to a large 

 size, serving often as a nest and food to the young larvae. 



The AsilidcB belong to the second division of the Diptera, and 

 are very active insects, which have a very formidable sucker, for 

 the two mandibles being completely soldered together form a 

 very sharp and piercing blade. The species are very numerous, 

 and are strong predatory insects, living upon live flies, and even 

 upon bees, which they chase and soon kill. Their flight is strong, 

 and they make a loud buzzing noise when on the wing. Some, 

 which have elongated bodies, a short trunk, and a formidable 

 sucker, attack horses and cattle, and sometimes man, and they 

 pierce the skin and suck the blood. One of the commonest 

 European species, Asihis crabroniformis, is decorated like some 

 of the Hymenoptera, and when it begins to suck produces the 

 same pain as that inflicted by a sharp lancet. It often attacks 

 large animals, but usually it sucks the blood of insects, and 

 especially of caterpillars. 



This insect, which is so bloodthirsty in adult age, appears to 

 be a vegetarian when in the condition of a larva. The larvae 

 are found underground, where they gnaw roots, and eventually 



