DIRECT BENEFITS DERIVED FROM INSECTS. 337 



ness, may be collected from the cocoons even of the 

 Ichneumons that destroy the larvae of some moth in the 

 West Indies which feed upon the indigo and cassada^. 

 It is probable, too, that other articles besides silk 

 might be obtained from the larvae which usually pro- 

 duce it, particularly cements and varnishes of different 

 kinds, some hard, others elastic, from their gum and 

 silk reservoirs, from which it is said the Chinese pro- 

 cure a fine varnish, and fabricate what is called by 

 anglers Indian grass''. The diminutive size of the ani- 

 mal will be thought no objection, when we recollect 

 that the very small Cj[uantity of purple dye afforded by 

 the Purpura of the ancients did not prevent them from 

 collecting it. 



I now conclude this long series of letters on the in- 

 juries caused by insects to man, and the benefits which 

 he derives from them ; and I think you will readily admit 

 that I have sufficiently made good my position, that the 

 study of agents which perform such important functions 

 in the economy of nature must be worthy of attention. 

 Our subsequent correspondence will be devoted to the 

 most interesting traits in their history, as their affection 

 to their young, their food and modes of procuring it, 

 habitations, societies, &c. 



I am, &c. 



'^ American Phil. Trans, v. 325, 



" Anderson's Recreations in JgiicitUnre, &c. iv. 399. 



VOL. I. 



