CH. XVIII.] PARASITICAL INSECTS, ETC. 259 



with a fine sheeting of resin. Sometimes, however, 

 it is more convenient for the insect to remove the 

 excrement altogether from its habitation. In this 

 case Degeer has seen it pushed out through a small 

 door, which has been subsequently closed with 

 fresh resin by the caterpillar. 



In some instances Degeer found no kernel within 

 the resinous gall; but even in these there was the 

 same attention to order and cleanliness exhibited as 

 in the others. The insect had partitioned off its 

 habitation by means of a resinous wainscoting, so 

 as to divide it into two chambers, in one of which 

 it lodged, while the other contained the excrement, 

 which it had pushed through a small door or hole at 

 the bottom of the dividing substance. The cater- 

 pillar feeds on the branch of the pine to which its 

 nest is attached, and gnaws into its substance. The 

 insect is about half .an inch in length. From its 

 conformation it would appear that air was neces- 

 sary to its existence, although the compactness of 

 the resinous galls appears to seal up their inhabi- 

 tant hermetically. About October, if these galls 

 be opened, the caterpillar will be found placed with 

 its head downwards, and so intensely torpid, that 

 even a rude touch does not put it in motion. In 

 this state it remains during the winter, against the 

 rigours of which, however, it has provided, by spin- 

 ning round itself a layer of silk. In the spring fol- 

 lowing it is reanimated by the sun, and now the 

 head of the insect is once more turned towards the 

 superior part of the resinous gall. 



It will be recollected that oil of turpentine is one 

 of the most deadly poisons to insects. The odour 

 of this substance penetrates their stigmata, or breath- 

 ing-pipes, and speedily kills them. One of the most 

 remarkable facts, therefore, connected with the his- 

 tory of our caterpillar is, that it should live and feed 

 on the very substance which is so fatal to its kin- 

 dred tribes. Degeer made experiments, all of which 



