468 HABITATIONS OF INSECTS. 



If you are desirous of examining the insects to which I 

 am alluding, you have only to place yourself by the side 

 of a clear and shallow pool of water, and you cannot fail 

 to observe at the bottom little oblong moving masses re- 

 sembling pieces of straw, wood, or even stone. These 

 are the larvae 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 conformation. Of the larva itself, which some- 

 what resembles the caterpillars of many Lepidoptera, no- 

 thing 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 toge- 

 ther 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 3 ; 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 b . 

 One, like the Sabella? , 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 P. bimaculata, which is 



* Plate XVII. Fig. 10. b Reaum.iii. 156-9. 



c Sowerbv's Nat, Miscell. No. ix. £.51. 



