And a curious thing about those which build of light pieces of bark or reed is this, that they will make the top-piece come over so as to hide their heads, and prevent you from seeing them. Some build of sand; and then as the house would be so light that the water running from the spring might wash it down and carry it away, the wonderful little creature takes care to anchor it by fastening a pretty large stone to it when it has nearly finished it. And as the worm anchors it when it is too light, so it lightens it when it is too heavy, by fixing a bit of light wood or hollow straw to it to buoy it up."
Sand Nest, balanced with a Stone.
Nest of Caddis-worm, balanced with Straws.
"Well, this is truly a wonderful insect. Uncle Philip."
"Truly so indeed, boys. In all these cases it uses its water-proof cement, and if you break its house to pieces, and will patiently watch, you may see it build another. The insect always lives with its head out of doors, and its body inside; so that its head is firm and hard, while its body is soft."
"Uncle Philip," said one of the larger boys, "there is one thing I have been thinking about, as you have been talking: these little masons have no trowel, but I believe I know of one animal that uses something like that tool."