Some others make much rougher houses.
You will be apt to find the caddice larvæ in any brook and in some ponds, and I hope you will always look for them.
Notice the tracery in the soft mud of the brook.
Those lines that look as though some one had been ornamenting the bottom of the brook are made by our caddice larvæ.
They drag their cases along and thus make these lines.
Sometimes such lines are made by the little fresh-water snails; but you can always find the decorator by following along the lines he makes.
What, May? How is the delicate larva able to cling to the case tightly enough to pull it along? If you look at it very carefully, you will find a pair of tiny hooks at the tail end by which it can hold on to the silk lining; and some caddice larvæ have hard points on their backs which help them to hold fast.
The caddice larvæ are carnivorous; that is, they eat animal food.
Yes, May, their food is usually the larvæ of other insects, but you will be glad to know that some of them eat plants too.