274 INDIRECT BENEFITS DERIVED FROM INSECTS. 



though many females appeared in the spring, scarcely 

 any neuters being to be seen in the autumn a ; and pro- 

 bably in consequence of this circumstance, flies in many 

 places were so extremely numerous as to be quite a nui- 

 sance. Reaumur has observed that in France the butchers 

 are very glad to have wasps attend their stalls, for the 

 sake of their services in driving away the flesh-fly ; and 

 if we may believe the author of Hector St. John's Ame- 

 rican Letters, the farmers in some parts of the United 

 States are so well aware of their utility in this respect, as 

 to suspend in their sitting-rooms a hornet's nest, the oc- 

 cupants 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 violet 

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

 a butterfly 5 . Linne informs us that Clenis form icarius 

 devours Anobium pertinax. A fly related to the Pa* 

 norpa communis appears created to instill terror into the 

 pitiless hearts of the tyrants of our lakes and pools, 

 the all-devouring Libellulina c . 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 Hymenoptera, by some unknown means instanta- 

 neously killing the insect they seize. Many species also 



a Mr. Knight made the same observation in 1806, and suppose* 

 the scarcity of neuters arose from the want of males to impregnate 

 the females. Phil-os. Tram, 1807, p. 243. 



b St. Pierre, Voy. 72. c Lesser, L. i. 263, note. 



