HABITATIONS OF INSECTS. 4^65 



of straw, wood, or even stone. These are the larva^ in 

 question, well known to fishermen by the title of Caddis- 

 worms, and which, if you take them out of the water, you 

 will observe to inhabit cases of a very singular confor- 

 mation. Of the larva itself, which somewhat resembles 

 the caterpillars of many Lcpidoptera, nothing is to be 

 seen but the head and six legs by means of which it 

 moves itself in the water, and drags after it the case in 

 which the rest of the body is inclosed, and into which 

 on any alarm it wholly retires. The construction of these 

 habitations is very various. Some select four or five 

 pieces of the leaves of grass, which they glue together 

 into a shapely polygonal case ; others employ portions of 

 the stems of rushes, placed side by side so as to form an 

 elegant fluted cylinder ; some arrange round them pieces 

 of leaves like a spirally-rolled ribband*; others inclose 

 themselves in a mass of the leaves of any aquatic plants 

 united without regularity; and others again form their 

 abode of minute pieces of wood either fresh or decayed''. 

 One, like the Sahdlce'^, forms a horn-shaped case com- 

 posed of grains of sand, so equal in size, and so nicely and 

 regularly gummed together, the sides throughout being 

 of the thickness of one grain only, that the first time I 

 viewed it I could scarcely persuade myself it could be the 

 work of an insect. The case of Lcptoccrus himaculatus, 

 which is less artificially constructed of a mixture of mud 

 and sand, is pyriform, and has its end curiously stopped 

 by a plate formed of grains of sand, with a central aper- 

 ture''. Other species construct houses which may be 

 called alive, forming them of the shells of various aquatic 



"Plate XVII. Fig. 10. " Rgaum. iii. 156-9. 



" Sowerbv's Nat. Miscell. No. ix. t.h\. <> De Geer, ii. r)64. 



VOL. I. 2 II 



