CADDIS WORMS. 155 
inch long, formed chiefly of Duckweed (Lemma sp.). Another, scarcely 
more than a quarter of an inch long, was of Duckweed on a foundation 
of (or mixed with) material like pale, short, very minute, round stems. 
Several of the ‘‘ cases” appeared to be wholly of vegetable matter, 
partly of the very little roundish scale-like leaves (or more correctly 
“fronds’’) of Duckweed, which all of us who have to do with ponds or 
ditches know well in the sheets in which it usually floats on the water 
in summer (these patches being composed, in the case of one of the 
commonest kinds, of multitudes of little leaf-like plants, each only 
about one-eighth to one-fourth of an inch across, formed of a flat 
green frond, with a single root fibre hanging down from it in the 
water). Also there were small pieces of leaf material which, from the 
irregular shape of the edges, seemed very probably to have been 
gnawed from Watercress leaves. 
The substratum (usually) of the vegetable ‘‘ cases” was of short 
cylindrical pieces of very uniform appearance, and apparently of roots 
of the Duckweed. ‘These were laid very prettily side by side,—several 
laid together in one direction, and several together crossing their ends 
in another direction, like ornamental cane-work. 
The grubs inside some of these were active, and the serviceableness 
of their long legs in helping them to progress by lapping them over 
each side of a blade of grass was very observable. In making their 
way where there was nothing to hold by,—as, for instance, when on 
the back of my hand,—I noticed the grub made use of its jaws as a 
partial help to drag itself on by. 
The Caddis ‘‘cases’’ may be made of any material which lies 
conveniently at hand for the grub to spin together for its shelter; the 
prettiest form is that made of small shells. Within these “ cases” 
the larva turns to the pupa condition, in which state they leave the 
now useless house a little before turning to the perfect Caddis Fly, or 
Water Moth. In an instance noticed by Prof. Comstock,” the time 
required for the insect to expand its wings and take its first flight was 
scarcely more than one second :—‘‘ The instant the creature was free 
from the water, its wings expanded to their full size, and immediately 
it flew away several feet.” 
The perfect insects, perhaps best known as Water Moths, have 
four membranous wings, turned well down at the sides when at rest; 
these more or less hairy, with few cross veins; legs long; mouth 
parts rudimentary ; antenne hair-like. 
The eggs are laid in gelatinous masses, said to be retained for 
some time at the extremity of the body, and then attached to some 
water plant. 
* See ‘ Manual for the Study of Insects,’ by J. Comstock, Professor of Entomo- 
logy in Cornell University, Ithaca, New York, U.S.A. 1895. 
