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NATURAL HISTORY OF ARTHROPODS. 



FIG. 578. Halesidota caryce. 



on the segments. They grow paler with each moult, and, after feeding about a month, 

 reach maturity, and lose their tubercles, except the one on the eleventh segment, 

 which takes the form of a curved, tapering horn, much like that on many of the 

 Sphingidse. The caterpillars are then about two inches long, of a dull-bluish color, with 

 small heads, and having the surfaces of the three segments following, thrown up into 

 wrinkles. On the top of the sixth segment is a pair of darker-blue lunate marks. The 

 cocoons which they spin have an outer covering of loose or floss silk, within which the 

 silk is more dense. They are oval in form, and pale yellow, or sometimes pure white, 

 cream colored, green or rose colored. The insects remain in the pupa state about 

 three weeks, at the end of which time they emerge, the sexes pair, and the females lay 

 their eo-gs, after which they die. The moths expand a little more than an inch, and 

 are cream colored, with two more or less distinct lines across each fore wing. Neither 

 sex flies, but the males are more active than the females. 



The hickory tussock-moth, Halesidota caryce, is a common species throughout the 

 Atlantic states and Canada, at times becoming so abundant as to do a great amount 



of damage. They are not limited as to food plants, 

 for they seem to thrive equally well on the leaves 

 of hickory, walnut, ash, elm, butternut, sumac, 

 beech, birch, alder, apple, and plum. When the 

 caterpillars are mature, they leave the trees, and 

 in some protected place, make their thin oval co- 

 coons which are composed of their hairs mingled 

 with silk, which they spin. Here they change to 

 pupa?, and remain till the following summer, when the moths emerge. The moths 

 expand about two inches, the fore wings being of a light ochre-yellow color, dusted 

 with dark brown, especially along the veins, with five transverse rows of silvery white 

 spots. The hind wings are much shorter than the fore wings, and of a paler yellow. 



The group of Arctians possesses many beautiful forms, possibly the handsomest of 

 our species being Arctia virgo. This moth spreads about two and a half inches, its 

 fore wings are salmon or flesh color, marked with broad black stripes, while the hind 

 wings are vermilion, ornamented with black dots. 



Arctia nais is widely distributed in this country, from the Gulf of Mexico to 

 Canada and from the Atlantic to the Pacific. It is so extremely variable in its mark- 

 ings that it has been described under nine different names, 

 and Drury himself gave names to at least two of the 

 forms. It expands an inch and a half or more, and the 

 wings are pale yellow. Sometimes a tinge of red is ob- 

 served on the base of the hind winsfs and sides of the 



~ 



body. There are two wide black stripes on the fore 

 wings, the hinder one extending from the base nearly to 

 the anal angle ; the other, from the base to the end of 



the cell. On the outer part of the wings are about four triangular and quadrate black 

 spots ; but there is great variation in the amount of black, the spots sometimes being 

 more or less fused together. The hind wings have several black spots near the outer 

 margin ; and in some examples these are so large as to run together, leaving only a 

 little of the ground color at the base of the winofs. 



d> ^j 



The eggs, which are laid in clusters of thirty or more on the strawberry and dande- 

 lion, are somewhat conical, smooth, and white, and hatch in five or six days. The cater- 



FiG. 579. Arctia nais. 



