14 IMPERFECT SOCIETIES OF INSECTS. 



however, keep longer together, and seldom wholly se- 

 parate. In their final state, I have noticed that the in- 

 dividuals of Thrips PIiT/sapus^ the fly that causes us in 

 hot weather such intolerable titillation, are very fond 

 of each other's company when they feed. Towards the 

 latter end of last July, walking- through a wheat-field, 

 I observed that all the blossoms o{ Convolvulus arvensis, 

 though very numerous, were interiorly turned quite 

 black by the infinite number of these insects, which 

 were coursing about within them. 



But the most interesting insects of this order are 

 those which associate in all their states. — Two popu- 

 lous tribes, the great devastators of the vegetable 

 world, the one in warm and the other in cold climates, 

 to which I have already alluded under the head of emi- 

 grations — you perceive I am speaking o^ Aphides and 

 Locusts — are the best examples of this order: although, 

 concerning the societies of the first, at present we can 

 only say that they are merely the result of a common 

 origin and station : but those of the latter, the locusts, 

 wear more the appearance of design, and of being pro- 

 duced by the social principle. 



So much as the world has suffered from these ani- 

 mals', it is extraordinary that so few observations have 

 been made upon their history, economy, and mode of 

 proceeding. One of the best accounts seems to be 

 that of Professor Pallas, in his Travels into the South- 

 O'ti Provinces of the Russian Empire. The species to 

 which his principal attention was paid appears to have 

 been the Gryllus ilalicus^ in its larva and pupa states. 

 "In serene warm weather," says he, " the locusts are 



» Soe Vol. I. 2il Ed. 214. 



