Packard.] 
INSECTS AS ARCHITECTS. 
309 
convert them into sacks which they bear about with them, 
much as in the caddis worms. The young clothes moth 
(Fig. 243, a, its sack; 6, chrysalis) bites off pieces of the 
woollen cloth on which it feeds, sticks them together by 
means of a silky secretion, and thus forms a close, dense 
sac. As it grows, instead of throwing away the sac it has 
outgrown, it makes a slit on each side, fills in the rent with 
new material, and adds more to the mouth, thus enlarging 
and refitting its house. 
Certain small caterpillars of the Acrobasis and other allied 
genera economize their excrement, constructing between the 
Fig. 241. 
Mauy-chambercd Grape Gall. 
leaves of the birches, on which they feed, little trumpet¬ 
shaped cases out of the little black pellets. • 
The case of the “basket worm” is a curious object. Fig. 
244 (a, moth ; 6, wingless female ; c, larva; c?, case) repre¬ 
sents the different stages of growth of a small species found 
in Florida by Mr. T. Glover. Our common basket worm is 
a familiar object in the middle and southern states. Its 
case is about two inches in length, and while the interior is 
lined densely with silk, on the outside are stuck pieces of 
cedar twigs and leaves, sometimes half an inch in length. 
We have seen the young just after leaving the egg beginning 
to build their cases, which are at first broad and shallow like 
a basket; and it is a comical sight to see the little tiny 
worms creeping rapidly along, their tails held straight up in 
21 
