270 INDIRECT BENEFITS DERIVED FROM INSECTS. 



off. An observing friend of mine a , who was some time 

 in Antigua, informed me that in that island, a kind of ant 

 which construct their nests in the roofs of houses, when 

 they meet with any animal larger than they can carry off 

 alive, such as a cockroach, &c, will hold it by the legs 

 so that it cannot move, till some of them get upon it and 

 dispatch it, and then with incredible labour carry it up 

 to their nest. Madam Merian, in her account of the 

 periodical ants mentioned to you before 1 ', and which is 

 confirmed by Azara c , notices their clearing the houses 

 of cockroaches and similar animals; and the Formica 

 omnivora is very useful in Ceylon in destroying the for- 

 mer insect, the larger ant, and the white ant d . 



You are not perhaps accustomed to regard wasps and 

 hornets as of any use to us ; but they certainly destroy an 

 infinite number of flies and other annoying insects. The 

 year 1811 was remarkable for the small number of wasps, 

 though many females appeared in the spring, scarcely 

 any neuters being to be seen in the autumn ; 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- 



a R. Kittoe, Esq. »> p. 123. 



e Voyages,!. 185. d Percival's Ceylon, 307. 



e Mr, Knight made the same observation in 1806, and supposes 

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

 the females. Philos. Trans. 1807, p. 243. 



