8 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
and thirty oak leaves weighing three-fourths <>f a pound; besides this it has drunk 
not leu than one-half en ounce of water. So the food taken by a single silk-worm 
in fifty-ail days squall in weight eighty-six thousand times the primitive weight of 
the worm. Of this, about one-fourth of a pound becomes excrementitious matter j 
207 grains ere assimilated and over .6 onnoea have evaporated. What a destruction 
of leaves this sin^lr species of insect could make if only a oue-hundredth part of 
the eggs laid came to maturity. A few years would be sufficient for the propaga- 
tion of a uuinber large enough to devour all the leaves of our forests." The 
Lepidoptera are almost without exception injurious to vegetation, and are among the 
chief enemies of the agriculturist. 
In our descriptions of the larvae of Lepidoptera the following points 
are noticed: Behind the head are twelve segments; the first or pro- 
thoracic is, in the small leaf- rolling and mining kinds, protected by a 
"cervical" or prothoracic shield; there are three thoracic segments, 
called the prothoracic, mesothoracic or metathoracic, or sometimes the 
first, second, and third thoracic segments; these correspond to the thorax 
of the imago or adult butterfly or moth. Behind these are nine distinct 
abdominal segments; on the eighth is often situated a dorsal hump. 
Many caterpillars are striped with a dorsal, subdorsal, and lateral lines 
or bands, moreover, the body in many is provided with warts or tuber- 
cles beating a hair or spine; the "lateral ridge" is a broken swelling 
extending along the sides of the body. The abdominal feet are in cer- 
tain leaf miners wanting; or in the span or geometrid worms there are 
but two pairs; and the last or "anal legs" are often broad and large, 
the better adapted for seizing firm hold of a leaf or twig. 
While a few butterflies live in the caterpillar state on trees, the fol- 
lowing brief synopsis gives the most salient characteristics of the 
families of moths which especially abound on the leaves of shade and 
forest trees : 
Moths of large size; larvae with a horn on the eighth abdominal segment.. Sphingidce. 
Moths with stout hairy bodies and small heads and broad wings; larvae more or less 
hairy or with spines; usually spinning silken cocoons Bombycidce. 
Moths of moderate size: stout bodies; shining hind wings; larvae with five pairs of 
abdominal legs; sometimes semi-loopers Xoctuidce. 
Moths with slender bodies, broad wings, both pairs colored alike ; larvaB with only 
two pairs of abdominal legs; span-worms or geometrids PhaJwrnda. 
Small moths with narrow, straight fore-wings, the hind wings plain ; larvae glossy 
green or pale, the head spotted, and the body more or less striped Pyralidcp. 
Still smaller moths, the fore-wings more or less oblong; the larvae green, with dark 
heads aud cervical shields ; not striped ; rolling leaves or eating buds. . Tortricidce. 
Minute moths with narrow, pointed wings; larvae small, pale greenish, etc., with a 
darker head and cervical shield ; often mining leaves, buds, etc Tineidas. 
Forest trees, and especially evergreen trees, support each year hordes 
of caterpillars, comprising species of diflereut families. In beating the 
branches of any spruce, fir, larch, poplar, or mapl^, and especially the 
oak, a great number and variety of caterpillars are shaken down, and 
the question arises whether the innumerable host constantly aud ordi- 
narily at work from spring-time to the fall of the leaf m our forest 
trees are really injurious to the tree. It is not improbable that good 
