STATES OF INSECTS. 155 



which these radii themselves are beautifully pinnated by 

 a fringe of longish spines on each side. Reaumur has de- 

 scribed the grub of a beetle, the genus of which is uncer- 

 tain, and which feeds upon the larva of Aleyrodes Prole- 

 tella, whose body is margined on each side by eight tri- 

 angular fleshy mammular processes, terminating each in 

 a bristle, which give it a remarkable aspect a . The cu- 

 rious scent-organs with which the larva of Chrysomela 

 Populi is fringed have been before fully described ; and 

 therefore I shall only mention them here b . 



In the larvae of the lace-winged flies (Hemerobius), and 

 ant-lions (Myrmeleon\ the anus is furnished with a small 

 fleshy retractile cylinder, from which proceeds the silken 

 thread that forms the cocoon inclosing the pupa c . Pro- 

 vidence has many different ways of performing the same 

 operation. From the structure of the oral organs of 

 these animals, the silk could not conveniently be fur- 

 nished by the mouth ; the Allwise Creator has therefore 

 instructed and fitted them to render it by a spinneret at 

 the other extremity of the body. 



The respiratory anal appendages of many Dipterous 

 larva? will be fully described in a subsequent Letter : I 

 shall therefore now only further observe upon this subject, 

 that although there is seldom any alteration in the form of 

 these appendages &c. in the same species, the caterpil- 

 lars of two moths (Centra Vinula and Attacus Tau)> how- 

 ever, are exceptions. The former, when young, has two 

 hairy projecting ear-like protuberances, which it entirely 

 loses, as I have myself observed, before it assumes the 

 pupa; and the latter, in like manner, after its third 



11 Reaum. ii. t. xxv.f. 20. 



b See above, Vol. II. p. 245 — . 



c Reaum. iii. 384. vi. 366. t. xxxii./, 7, 8. 



