INDIRECT BENEFITS DERIVED FROM INSECTS. 271 



eupants of which prey upon the flies without molesting 

 the family. 



There are other devourers of insects in their perfect 

 state, the manners and food of whose larvae we are un- 

 acquainted with. St. Pierre speaks of a lady-bird, but 

 it probably belonged to some other genus, of a fine vio- 

 let colour, with a head like a ruby, which he saw carry 

 off' a butterfly 1 . Linne informs us that Cleras formica- 

 rius devours Anobium pertinax. A fly related to the 

 Panorpa communis appears created to instill terror into 

 the pitiless hearts of the tyrants of our lakes and pools, 

 — the all-devouring Libellulidce b . The Asili also, which 

 are always upon the chase, seize insects with their an- 

 terior legs and suck them with their haustellum. The 

 cognate genus Dioctria, particularly D. celandica, prey 

 upon Hxpnenoptera, by some unknown means instanta- 

 neously killing the insect they seize. Many species also 

 of Empis, whose haustellum resembles the beak of a bird, 

 carry off in it Tipulidcs and other small Diptcra ,■ and 

 what is remarkable, you can seldom take these insects in 

 coitu, but the female has a Tipula, some fly, or some- 

 times beetle, in her mouth. Can this be to deposit her 

 eggs in, as soon as they are impregnated by the male? 

 or is it designed for the nuptial feast ? Even Scatophaga 

 stercoraria (Musca, L.) and scybalaria, and probably 

 many others of the same tribe, feed upon small flies, 

 though their proboscis does not seem so well adapted for 

 animal as for vegetable food. 



The most unrelenting devourers of insects appear to 

 be those belonging to my fourth division, which attack 



a . St. Pierre, Voij. 72. b Lesser, L. i. 263, note. 



