INDIRECT BENEFITS DERIVED FROM INSECTS. 273 



flesh-fly; and if we may believe tlie author of Hector 

 St. John's Aynericaji Letters^ the farmers in some parts 

 of the United States are so well av*are of their utility 

 in this respect, as to suspend in their sitting-rooms a 

 hornet's nest, the occupants of which prey upon the ilies 

 without molesliii;^- the family. 



There are other devourers of insects in their perfect 

 state, the manners and food of whose larvjE 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^. Linnc informs us that Clerus formica' 

 rius devours Atiobium pcriinax. A fly related to the 

 Paiiorpa communis appears created to instill terror into 

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

 — the all-devouring Libellulidce^ . 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 Ilymenoptera, by some unknown means instan- 

 taneously killing the insect they seize. Many species 

 also of Empis, whose haustellum resembles the beak of 

 a bird, carry off in it TipitUdce and other small Diptera ; 

 and V, hat is remarkable, you can seldom take these in- 

 sects in coitu, but the female has aTipula, some fly, or 

 sometimes beetle, in her mouth. Can this be to depo- 

 sit her eggs in, as soon as they are impregnated by the 

 male? or is it designed for the nuptial feast? Even 

 Scatophaga stercoraria {Musca tj.) and scyhalaria^ and 

 probably many others of the same tribe, feed upon small 



* S«. Pierre, Foy.T2. " Lesser. L. i. 263, note. 



VOL. I. X 



