396 
The Moths and Butterflies 
as they are variously called, which are the larvae (caterpillars) (Fig. 565) 
of the moths of the superfamily Geometrina (earth-measurers). These 
three common names as well as the scientific one refer to the peculiar mode 
of locomotion affected by all the Geometrina. Each loop or step is made by 
the bringing forward of the caudal extremity of the body quite to the thoracic 
feet, the portion of flexible body between 
bending up and out of the way each time 
during the process. The reason for it 
all will be understood when the inch- 
worm is examined. It differs from other 
Fig. 566. —Lime-tree inch-worm, larva 
of the geometrid moth, Hibernia 
tiliaria. (After Pettit; twice natural 
size.) 
ri r? r 3 
lepidopterous larvae in lacking the front 
three of the four pairs of prop-legs 
normally belonging to the middle part 
of the body, which is thus rendered 
helpless in walking, and the curious looping gait is the outcome of the pos¬ 
session by a long slender flexible body of only anterior and posterior locomotory 
organs (Fig. 566). Why inchworms are not more often seen, although there 
are hosts of different kinds of them and they 
are well distributed and common all over the 
country, is due to their habit of “ going 
stiff” when disturbed, clinging by the hinder 
two pairs of legs to the twig or leaf and 
holding the rest of the body motionless and 
rigid at an angle with the support. As the 
body is always protectively colored and 
marked, so as to harmonize thoroughly with 
the habitual surroundings many an inch- 
worm may be seen but not distinguished 
from the leaf or branch on which it rests. 
Indeed, many of the inchworms are amaz¬ 
ingly like a short or broken twig, with buds 
or leaf scars and lined or scaly bark, a very 
effective case of protective resemblance. 
The geometer-moths, of which we have 
800 species in this country, while of course 
presenting a great variety of coloration and 
pattern yet possess a likeness of general 
appearance due mostly to the slenderness of 
body compared with the broadness of wings, the impression of fragility or thin¬ 
ness of wings due to the unusually fineness of the covering scales, and the deli¬ 
cate and quiet coloration and patterning, which indicate their identity pretty 
effectively. Some are small, i.e., less than 1 inch expanse, and a few large, 
Fig. 567.—Venation of a geometrid, 
Dyspepteris abortivaria. cs, cos¬ 
tal vein; sc, subcostal vein; r, 
radial vein; in, medial vein; 
c , cubital vein; a, anal veins. 
(After Comstock; enlarged.) 
