“Their cases are stuck to the pond weeds and to each other,” said Frank, as he lifted a few out, and placed them in a saucer.
“Ah, I have it, Uncle George! They have gone into the pupa state. Is that not so?”
Uncle George nodded.
“Look!” exclaimed Tom. “There are things like earwigs floating on the water.”
“Never mind these just now, Tom,” said his uncle. “I am coming to them by and by. Observe the wonderful cases which the caddis worms have made for themselves.
“Here is one whose case, when we found him, was made of neatly cut pieces of water rush. He has almost doubled the length of his case since then; for see, the front half is made of cut stalks of water weed neatly arranged.”
“He has got a fine collar of green pieces round his neck,” Frank observed.
“Why are they always adding to the length of their cases?” asked Tom.
“Because they are always growing,” said Frank.
“That is the reason,” said Uncle George; “and they grow so fast that they have actually to work hard at building.