242 TEESH-WATEE AQUAKIA. 



forcibly drag ttem out would only end in their being pulled in 

 half — or, at any rate, in their death. But they may easily be 

 dislodged by inserting the stalk of a leaf or a very thin piece 

 of stick into the end at which is the extremity of the insect. 

 This part of the tube is generally of smaller diameter than 

 the other, and the animal will nearly always, after a little 

 tickling, evacuate its fortress. Sometimes the larvae wiU 

 voluntarily leave their cases; but whether they have been. driven 

 out of their homes, or have left of their own accord, they will 

 generally return to them upon the first opportunity. 



It is a very interesting sight to see these clever little 

 architects and builders at work. Upon being taken from their 

 cases and placed naked, along with suitable material, in a 



Fig. 151. Larv^ op Different Species of the Caddis-fly, and 

 THEIR Cases. 



saucer or other vessel, they wiU readily make new tubes. 

 They can be persuaded to construct their dwellings of pieces 

 of coal, bits of glass, beads, filings of metal, and other things 

 of a similar kind. Some caddis-worms work much more qxuckly 

 than others, but the speed of construction frequently depends • 

 upon the materials at hand. 



There are in Great Britain about one hundred and sixty 

 different species of Caddis-flies, which have been divided by 

 Mr. McLachlan, the author of the "Monographic Revision and 

 Synopsis of the European Trichoptera," into seven families. 

 Of these families, that of the PhrygoMeidse (Gr. phruganon, 

 a bundle of sticks) contains the largest species ; and that of 

 the Limnophilidx the most numerous. It wHl, of course, be 

 impossible to refer in this chapter to anything like all the 



