PERFECT SOCIETIES OF INSECTS, 111 



have enlarged in a former letter^. The workers also 

 clean the ceils and prepare them to receive another egg, 

 after the imago is disclosed and has Jieft it. 



There is good reason for thinking, and the opinion has 

 the sanction of Sir Joseph Banks, that wasps have senti- 

 nels placed at the entrances of their nests, which if you can 

 once seize and destroy, the remainder will not attack you. 

 This is confirmed by an observation of Mr. Knight's in 

 the Philosophical Transactions '', that if a nest of wasps 

 be approached without alarming the inhabitants, and all 

 communication be suddenly cut off between those out of 

 the nest and those within it, no provoca!tion will induce 

 the former to defend it and themselves. But if one es- 

 capes from within, it comes with a very different temper, 

 and appears commissioned to avenge public wrongs, and 

 prepared to sacrifice its life in the execution of its orders. 

 He discovered this when quite a boy. 



It sometimes happens, that when a large number of fe- 

 male wasps have been observed in the spring, and an 

 abundance of workers has in consequence been expected 

 to make their attack upon us in the summer and autumn, 

 but few have appeared. Mr. Knight observed this in 1 806", 

 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, noticed in the year 1815. 

 What took place here in the following year may in some 

 degree account for it. Though the summer had been 

 very wet, and one may almost say winterly, there were 

 in the neighbourhood in which I reside abundance of 

 wasps at the usual time; but, except on some few warm 



^ Vol. I. p. 501. " For 1807, 242— « Ibid. 243. 



