CADDIS-FLIES. 289 ' 



of this ji;elatinous secretion, which has the capacity of resisting 

 water, tlie eg'g-cluster is affixed to the stem of some subaquatic 

 plant, and there left to be hatched in due time. The duties of 

 the mother Caddis-fly being then over, she perishes, either by 

 natural decay, or by means of some fish, which doubtlessly 

 thinks itself deceived in having been induced to eat a mere 

 sliell of an insect, as is the Caddis after she has deposited her eggs. 



When the little larvas emerge from the egg, they set to 

 work in forming for themselves the remarkable habitations in 

 which they pass the whole of their larval and pupal existence. 

 Being long, soft-bodied creatures, with only the head and neck 

 defended by a horny covering, they would fall victims to 

 various predacious inhabitants of the water, if they possessed 

 not the power of forming for themselves some sort of pro- 

 tection. P"'ollowing the general rule under such circumstancet;, 

 the protection in question assumes the shape of a case more or 

 less cylindrical, and is capable of being enlarged in proportion 

 to the growth of the inhabitant. 



As has been already mentioned, these habitations are made 

 of various materials, and are all more or less cylindrical as far 

 as regards their interior, though in many instances their 

 exterior departs as far as possible from that shape. 



For example, one or two of the si^ecies always select dead 

 leaves, which they fit together, face to face, so that scarcely 

 anyone on seeing them would imagine that between the leaves 

 was the tubular residence of a Caddis-worm. Sometimes, as in 

 Phi'yganea rhombica, short pieces of grass stems are used, which 

 are cut into tolerably equal lengths, and fixed across each other 

 so as to leave a hollow in their centre. Sometimes, as in 

 Phryganea lunaris, the pieces of grass are much longer, and 

 laid side by side. Some species, such, for example, as Phn/- 

 ganea fusca, use the shells of various aquatic molluscs, which 

 they fasten together without the slightest reference to the 

 feelings of the inhabitants, some of which may be seen vainly 

 trying to progress in one direction, while the Caddis-worm is 

 crawling in another. Examples of these two last-mentioned 

 forms may be seen in Plate VIII. Fig. 8. Some species, such 

 as Sericostonia midtiguttatum, employ particles of sand, 

 tiny stones, and similar materials, forming them into a conical 

 case with a slight curve, very much resembling in shape an 



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