312 INSECTS OF MASSACHUSETTS. 



resting only on the four intermediate pairs of legs. If touched 

 or otherwise disturbed, they throw up their heads and tails with a 

 jerk, at the same time bending the body semicircularly till the 

 two extremities almost meet over the back. They all eat togeth- 

 er, and, after they have done, arrange themselves side by side 

 along the twigs and branches which they have stripped. Begin- 

 ning at the ends of the branches they eat all the leaves succes- 

 sively from thence towards the trunk, and if one branch does not 

 afford food enough they betake themselves to another. When 

 ready to transform, all the individuals of the same brood quit the 

 tree at once, descending by night, and burrow into the ground to 

 the depth of three or four inches, and, within twenty-four hours 

 afterwards, cast their caterpillar-skins, and become chrysalids 

 without making cocoons. They remain in the ground in this 

 state all winter, and are changed to moths and come out between 

 the middle and end of July. These moths belong to the genus 

 Pygcera, so named because the caterpillar sits with its tail raised 

 up. The antenna; are rather long, those of the males fringed 

 beneath, in a double row, with very short hairs nearly to the tips, 

 which, however, as well as the whole of the stalk of the antennae 

 in the other sex, are bare ; the thorax is generally marked with 

 a large dark-colored spot, the hairs of which can be raised up so 

 as to form a ridge or kind of crest ; the hinder margin of the 

 fore-wings is slightly notched ; and the fore-legs are stretched out 

 before the body in repose. Our Pygcera was named, by Drury, 

 ministra, the attendant or servant. It is of a light brown color ; 

 the head and a large square spot on the thorax are dark chestnut- 

 brown ; on the fore-wings are four or five transverse lines, one 

 or two spots near the middle, and a short oblique line near the tip, 

 all of which, with the outer hind margin, are dark chestnut-brown. 

 One and sometimes both of the dark brown spots are wanting on 

 the fore-wings in the males, and the females, which are larger 

 than the other sex, frequently have five instead of four transverse 

 brown lines. It expands from one inch and three quarters to 

 two inches and a half. 



I have seen on the oak, the birch, the black walnut, and the 

 hickory trees, swarms of caterpillars slightly differing in color 

 from each other and from those, above described, that live on the 



