STATES OF INSECTS. 85 



of these introduce them into living animals, and then 

 leave them to their fate, as the Ichneumons and gad-flies: 

 others deposit them along with the dead body of an in- 

 sect interred in a hole, often prepared with great labour, 

 as the different species of sand-wasps (Sphecidce), spider- 

 wasps (Pompilidcc), &c. : the manners of the latter of these 

 tribes have been already adverted to a , and those of the 

 Ichneumonidce will come more fully under consideration 

 when I treat of the diseases of insects. 



A similar labour in providing suitable habitations for 

 their eggs is undergone by vai'ious other insects whose 

 larvae live chiefly on vegetable food, some inserting their 

 egg within the substance the larva devours, as those that 

 prey on timber, twigs, roots, or the like, and others on 

 its surface. One would suppose at first, that the exceed- 

 ingly small egg which produces the subcutaneous larvae 

 would, by the parent moth, be imbedded in the substance 

 of the leaf which is to exhibit hereafter their serpentine 

 galleries : but this is not the case, for she merely glues it 

 on the outside ; at least such was the situation of the only 

 egg of these very minute moths Reaumur had ever an 

 opportunity to observe b . 



Other insects, belonging to the tribe which lay their 

 eggs singly, bury them in the ground. Of this descrip- 

 tion are many of the lamellicorn insects, the dung-chafers 

 (Scarabceidcs MacLeay) particularly, which, inclosing 

 their eggs in a pellet of dung, deposit them in deep cy- 

 lindrical cavities. Concerning the proceedings of some 

 of these, as well as of the whole race of bees, wasps, &c, 

 which all lay single eggs, I have before detailed to you 



a See above, Vol. I. p. 344—. b Reaum. iii. 8—. 



