32 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
manner, instead of the narrow girdling band, had had the bark irregu- 
larly removed for theextent of aninchor more. All these later falling 
twigs showed the interval that had elapsed between the injury and the 
fall, in that the roughened edges of the bark left by the gnawing had 
healed over with the peculiar roughened and rounded enlargement fol- 
lowing the deposit of the reparative material under such conditions, 
Some of the twigs gathered gave excellent illustration of the ascent of 
the sap through the outer wood, and its return, after assimilation in the 
leaves, through the inner bark. In one instance, where the leaves were 
unusually large, the descending sap, arrested at the girdled point, had 
built up structure in the tip until its diameter was more than double 
that of the starved internode below, while the immediate point of the 
arrest Was quite enlarged from the material there deposited. 
“This peculiar attack did not extend to the other principal food- 
plants of the Orgyia, as the horse-chestnut, maple, apple and plum, 
nor would it be expected to occur in connection with growth and struct- 
ure so different from that of the elm.” 
Pupation.-Six days after the third molt a portion of the larve spin 
up; all these produce male moths. The female caterpillars, which up 
to this time have been undistinguishable from the male caterpillars, 
undergo a fourth (and, as it appears from more recent experience, in 
some instances even a fifth) molt and acquire twice the size of the 
male caterpillar. This last, when full grown, measures about 20 milli- 
meters inlength. The cocoon spun by the male caterpillar is of whitish 
or yellowish color and sufficiently thin to show the insect within. It 
consists of two layers, the hairs of the tufts and brushes of the cater- 
pillar being interwoven with the outer layer. The female cocoon is 
correspondingly larger, of gray color, aud much more solid and denser 
than the male cocoon. The male chrysalis (Fig. 13 d), which is soon 
formed within the cocoon, is of brownish color, sometimes whitish on 
the ventral side, and covered on the back and sides with fine white 
hairs. The female chrysalis (Fig. 13¢) is much larger than the male, 
an otherwise differs, especially in lacking the wing-sheaths and in bav- 
ing on the three first segments after the head transverse, flattened pro- 
tuberances composed of scales, which are much less visible in the male. 
The duration of the pupa state is less than a fortnight. 
The Imago.—The male (Fig. 15) is a winged moth with feathery an- 
tenn and very hairy fore legs. The general color is ashy-gray, the front 
wings being crossed by undulated bands of darker 
shade, with two black markings on the outer edge 
near the tip and a-white spot on the inner edge also 
| near the tip. He may frequently be seen sitting on 
|} the trunks of trees or on the shady side of houses, etc., 
as he rests during the day, and flies only after dusk, 
often being attracted by light. The female (Fig. 13a) 
‘| is totally different from the male in appearance and 
Fic. 15.—Orguia leu. resembles a hairy worm rather than a moth, since she 
ce ee possesses the merest rudiments of wings. She is of a 
pale gray color, the antenn being short and not feathered, the legs 
