PARASITE-EGGS. 59 



Another parasite (Pimpla strobilellfB, Fabr.) is 

 F armed witli a long ovipositor, with which it deposits 

 its etrgs in larvae that burrow in the fruit-cones of 

 the fir. 



The intrusion of these parasite-eggs into the nests 

 of insects is often an exceedingly puzzling circum- 

 stance to naturalists, in their earlier researches ; and 

 sometimes even deceives those of considerable expe- 

 rience and acuteness into the supposition that the 

 insects ultimately produced are in reality those of 

 the original builder of the nest. These deceptions 

 frequently occur in the numerous species of vege- 

 table galls, originating chiefly in the economy of a 

 beautiful family of insects {ChalcidideBy Westwood). 

 When the gall-fly {Cynips^ has deposited its eggs on 

 the bud or the leaf of a plant in such a manner as to 

 ensure their being surrounded with a thick coating of 

 vegetable substance, they are not on that account se- 

 cure from the insects just alluded to; for the Chalets, 

 armed by nature with an instrument for the purpose, 

 ! can penetrate in any direction the largest oak-apple 

 i or bedeguar of the rose*. The most obvious dis- 

 tinction between these parasites and the true gall-flies, 

 is, that in the latter the ovipositor is partly concealed, 

 while in the former it is altogether external, like the 

 ichneumons in the preceding figure ; but this dis- 

 tinction is of course wanting in the male insects. It 

 was the observation of different species of insects, 

 produced in this manner from the same sort of gall, 

 which betrayed the illustrious Redi into the fancii'ul 

 notion of their being generated by a vegetative and 

 sensitive soul in the plant itself, to which also he 

 attributed the generation of the grubs found in nuts, 

 cherries, and other fruits. '' There is nothing," as 

 Reaumur justly remarks, *' more fitted to humi- 

 liate the best reasoners, and to inspire them with a 

 * See Insect Architecture, pp. 375 — 384. 



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