THE INSECT 'ORDERS.' 255 



5. The interesting order Neuroptera is the next 

 in succession, but it has been already sufficiently 

 described iu Chapter XI., when describing our 

 native and some of the exotic Dragon-flies. 



6. The order Trichoptera comprises those sin- 

 gular insects, the wings of some of which are scaled 

 like those of Lepidoptera, a few of the larvse of 

 which, with their curious cases of sand, shells, or 

 chips, should find a place in the Vivarium. The 

 whole number of the species of Caddis fly known 

 to Olivier was only seventy-seven, while, by more 

 persevering researches, M. Pictet of Geneva has 

 discovered a hundred and twenty distinct kinds in 

 Switzerland alone. 



7. The order Hymenoptera — that is, the trans- 

 parent-winged class— comprises a great number of 

 insects, and in that respect rivals Coleoptera, but 

 most of them are of rather small size. In many, 

 as the Bees and Wasps, all of which may serve as 

 types of this class, the larvae are maggot- formed— 

 that is to say, legless— but the larvae of the Sand- 

 flies very closely resemble the caterpillars of Lepi- 

 doptera, except in having a greater number of 

 ventral legs. The legless larvae of this order are 

 provided Avith food by the parents, as before de- 

 scribed, those of the Ichneumons being placed so 



