460 



NATURAL HISTORY OF ARTHROPODS. 



Fio. 57'^. — Ilalcsidota cari/re. 



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

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

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

 Sphingida3. 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 dai-ker-blue limate marks. The 

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

 silk is more dense. They are o\'al in form, and pale yellow, or sometimes pure white, 

 cream colored, o-reen 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 eggs, 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. Xcither 

 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, aldei-, 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 

 liu]><T, 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, especiall_v along the A'eins, with five transverse rows of silvery white 

 spots. The hin<l wings are much shorter than the fore wings, and of a jialer 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 tlie 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 ol> 

 served on the base of the hind wings 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 

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

 sj)ots ; 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 wings. 



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- 



FlG. 079. — Arctia 7}ais 



