PERFECT SOCIETIES OF INSECTS. Ill 



this subject I have enlarged in a former letter^. The 

 workers also clean the cells, and prepare them to re- 

 ceive another egg, after the imago is disclosed and has 

 left it. 



There is good reason for thinking, and the opinion 

 has the sanction of Sir Joseph Banks, that wasps have 

 sentinels placed at the entrances of their nests, which 

 if you can once seize and destroy, the remainder will 

 not attack you ; which is confirmed by an observation 

 of Mr. Knight's in the PhilGsophical Transactions^^ that 

 if a nest of wasps be approached without alarming the 

 inhabitants, and all communication be suddenly cutoff* 

 between those out of the nest and those within it, no 

 provocation will induce the former to defend it and 

 themselves. But if one escapes from within, it comes 

 with a very different temper, and appears commis- 

 sioned to avenge public wrongs, and prepared to sa- 

 crifice its life in the execution of its orders. He disco- 

 vered this when quite a boy. 



It sometimes happens, that when a large number of 

 female wasps have been observed in the spring, and an 

 abundance of workers has in consequence been ex- 

 pected to make their attack upon us in the summer and 

 autumn, but few have appeared. Mr. Knight observed 

 this in 1806, and supposes it to be caused by a failure 

 of males ^. I have since more than once made the same 

 observation, and Major Moor, as well as myself, no- 

 ticed it last year (1815). What took place here in the 

 present year (1816) may in some degree account for 

 it. Though the summer has been so wet, and one 

 may almost say winterly, there were in the neighbour- 



■ Vol. I. 2d Ed. p. 505. " For 1807, «42— "^ Ibid 243. 



