The Life of the Fly 



short, held in position by numerous guy-ropes, 

 is a base upon which a solid and definite struc- 

 ture will rise before long. Soon, the original 

 work will crumble to ruins and disappear, 

 whereas the new one, a permanent structure, 

 will even outlast the owner. 



The insects reared in a tumbler show yet 

 another method of building the first dwelling. 

 This time, the Caddis-worm is given a few 

 very leafy stalks of pond-weed {Potamogeton 

 densum) and a bundle of small dry twigs. 

 It perches on a leaf, which the nippers of the 

 mandibles cut half across. The portion left 

 untouched will act as a lanyard and give the 

 necessary steadiness to the early operations. 



From an adjoining leaf a section is cut out 

 entirely, an angular and good-sized piece. 

 There is plenty of material and no need for 

 economy. The piece is soldered with silk to 

 the strip which was not wholly cut off. The 

 result of three or four similar operations is 

 to surround the Caddis-worm with a conical 

 bag, whose wide mouth is scalloped with 

 pointed and vers^ irregular notches. The 

 work of the nippers continues; fresh pieces 

 are fixed, from one to another, inside the fun- 

 nel, not far from the edge, so that the bag 



J94 



