A CHAPTER OF LIFE-HISTORIES. 
79 
Possibly some of the larger nymphs in the aquarium 
may crawl up a stick or other object and, fastening 
their feet firmly, await their final metamorphosis from 
aquatic to aerial life. 
At this time the exo-skeleton of the nymph splits 
down the back and there emerges the beautiful creature 
we so often see hovering over the surface of streams 
and ponds. The two pairs of delicately veined wings 
Fig. 70.—Caddis-fly, Adult and Larval Cases. 
are never folded like those of the grasshopper or beetle, 
but remain extended even while the insect alights. 
The lower lip has lost its mask-like appendage, the 
mandibles are hard and toothed, the eyes are very 
large, the abdomen is long and tapering, the legs are 
small and bunched together for security in alighting. 
It is now a fine creature of wonderful agility and grace. 
Harmless to man and larger animals, it devours mos- 
