PARASITE INSECTS. 65 



Goedart, and disbelieved by Rf'aumur and subse- 

 quent naturalists: but we think it so very extra- 

 ordinary, that we are much inclined to think the 

 observer (T. H. of Clapliam) has unwittingly fallen 

 into mistake. ' Some of them,' he continues, ' ex- 

 ecuted the task; but the greater part were too feeble 

 to complete it; and in the course of three days 

 more they became motionless, and gradually, one 

 after another, fell shrivelled and exhausted to the 

 bottom of the cage.' Some of the clusters contained 

 upwards of a hundred cocoons, and others not more 

 than sixty. By July 12, the perfect flies made 

 their appearance by opening a sort of lid at the end 

 of each cocoon. The flies seem to differ little, 

 except in size, from the common ichneumon of the 

 same caterpillar (^Microgaster glomtralus ;) but, sup- 

 posing them to be in the first instance egg parasites, 

 they must have been deposited among, not in the 

 eggs of the butterfly. 



The minuteness of some of these parasite insects 

 may be partly conceived from the fact mentioned by 

 Bonnet, — that the egg of a butterfly, not bigger than 

 a pin's head, is sufficient to nourish several of them; 

 for out of twenty such eggs of butterflies, a pro- 

 digious number {ime quantite prodi2;ieiise) were 

 evolved.* Few species of the plant-lice (^Jlphides) 

 are a great deal larger than the butterfly's eggs de- 

 scribed by Bonnet; yet these also have a parasitical 

 enemy {Microgasler Aphidum, Spinola), which 

 plunges its eggs in their bodies; but the larvae, 

 when hatched, are by no means safe, being liable 

 to the attacks of another fly of the same family 

 {Gelis agilisj Thunberg), as Dr Turton informs 

 us.t 



* Bonnet, QEuvres, Svo, ii, 344. Kirby, referring to this 

 passage, assigns, by mistake, only two to each egg. Introd. 

 i, 342. 



t Transl. of Linu. iii, 48. 



VOL. VJ. 6* 



