248 ORDER LEPIDOPTERA. 



There seems to be considerable variation in the size and colors of this painted moth, 

 possibly due in part to sex. In the figure of Druuy, the anterior wings are daric, with 

 yellow marginal dots. A Catocala found in Western Massachusetts has the dark anterior 

 \rings and dotted margin ; while the moth is larger, the red belts of the hindwings are 

 brighter, and the posterior margin is almost ciliate and yellowish gray. But another, near- 

 ly as large, is pale and ashen, and the inferior wings have yellow instead of vermilion red. 

 Another still is small, about 1^ inch in expansion, with yellow also ; but has the angular 

 spot, and other markings similar in fashion to Druky's figure. 



There seem to be gradations both in size and depth of coloring, which are not sufficient 

 to distinguish species, but may establish varieties ; but as I have before me only six in- 

 dividuals, I may be mistaken in my estimate of the importance of their diflerences. 



Gcometridae. 



SPANWORMS, LOOPERS, &c. 



The insects of this family move over the ground, or along the branches of trees, in distinct 

 steps, as if measuring their progress, by alternately flexing and extending tlieir bodies from 

 point to point. The manoeuvre is performed by first extending the anterior extremity of the 

 body as far ahead as it will reach, and then bringing forward the posterior extremity by 

 elevating the middle portion of the body, so that the extremes are brought into contact, 

 and the whole takes the form of a loop ; and thus by successive steps they measure their 

 route according to the length of their bodies. Their legs, which are usually ten on each 

 worm, are employed rather in fixing the body at its successive points of rest, than in in- 

 dependent movements of the feet. They necessarily move slow ; and as they occupy bushes 

 and trees in feeding, and must seek the ground to undergo transformation, they are pro- 

 vided with the apparatus and means of spinning a thread, by which they are enabled to 

 let themselves quickly down to the ground ; and in cases of alarm they frequently do this, 

 remaining suspended until the danger is past, when they return to tlieir feeding by aid of 

 mouth and feet, seizing the thread above with the jaws, and then drawing up the body by 

 doubling it as before described. They are destitute of hairs. 



When the spanworm goes to rest, it fixes itself by the posterior feet, and lifts its body 

 up and sustains it stiffly in an angular and motionless posture, thereby counterfeiting the 

 appearance of a short broken dead twig of the branch on which it reposes, with the instinct 

 of eluding if possible the searching eyes and devouring beaks of hungry birds. 



To the Family GEOMETRioiE belong some of the most destructive moths, particularly 

 the cankerworms. Those which are injurious to fruit-trees have usually thin angulated 

 wings ; but they are wanting in the female, or merely rudimentary, and hence are very 

 unequal in this respect : this fact gave origin to the name aMisrjj^cna:, < unequal-wings.' 



