8 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



and thirty oak leaves weighing three-fourths of a pound ; besides this it has drunk 

 not less than one-half an ounce of water. So the food taken by a single silk-worin 

 in fifty-six days equals in weight eighty-six thousand times the primitive weight of 

 the worm. Of this, about one-fourth of a pound becomes excrementitious matter : 

 207 grains are assimilated and over 5 ounces have evaporated. What a destruction 

 of leaves this single species of insect could make if only a one-hundredth part of 

 the eggs laid came to maturity. A few years would be sufficient for the propaga- 

 tion of a number 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 larv?e 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 beaiiug 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 miuers 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 Bombi/cidce. 



Moths of moderate size: stout bodies; shining hind wings; larvae with five pairs of 



abdominal legs; sometimes semi-loopers Noctuidce. 



Moths with slender bodies, broad wings, both pairs colored alike; larvae with only 



two pairs of abdominal legs; span-worms or geometrids Phalw.nidce. 



Small moths with narrow, straight fore-wings, the hind wings plain ; larva) glossy 



green or pale, the head spotted, and the body more or less striped Pi/ralidw. 



Still smaller moths, the fore-wings more or less oblong ; the larvae green, with dark 



heads and cervical shields ; not striped ; rolling leaves or eating buds. . Tortricidw. 

 Minute moths with narrow, pointed wings ; larva; small, pale greenish, etc., with a 



darker head and cervical shield ; often mining leaves, buds, etc Tineidai. 



Forest trees, and especially evergreen trees, support each year hordes 

 of caterpillars, comprising species of different 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 and 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 



