396 



The Moths and Butterflies 



Fig. 566. — Limc-trcc inch-worm, larva 

 of the gcomrtrid moth, Uibernia 

 tiliaria. (After Pcltit; twice natural 

 size.) 



as they are variously called, which are the larva (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 t" 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 

 lepidopterous larwT 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 diftcrenl 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 

 licilding 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 

 I)re.senting 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 fmencss of the covering scales, and the deli- 

 cate and quiet coloration and patterning, which indicate their identity ])retty 

 effectively. Some are small, i.e., less than i inch expanse, and a few large, 



Fig. 567. — ^Venation of a gcometrid, 

 Dyspepteris aborlivaria . cs, cos- 

 tal vein; sc, subcostal vein; r, 

 radial vein; m. medial vein 

 c, cubital vein; a, anal veins. 

 (After Comstock; enlarged.) 



