Bombyx Acria, Fab. Ent. Syst. III. 1. p. 451. No. 137. Abbot and Smith, Ins. Georg. tab. 67. (exclus. Syn. Fabr. B. lubricepidæ).
Arctia Pseuderminea (Peck), Harris in Massachus. Agricult. Repos. vol. 7. p. 328. and tab. annex.
Habitat: New York, Maryland, Virginia (Drury).
Male..—Upper Side. The antennæ and eyes are black; the thorax and extremity of the body cream colour; he abdomen yellow, spotted on the top and sides with black. The anterior wings are cream coloured, spotted with black. The number of spots very uncertain, except five which are placed on the anterior edge, and six on the external one. The cilia yellow, as are the posterior wings, on each of which are three black spots, two near the external edge, and one near the middle.
Under Side. The breast and thighs are yellow; the abdomen and legs the same, chequered and spotted with black. All the wings are yellow, spotted in the same manner with black, as on the upper side.
Female.—Upper Side. The head and thorax white. The abdomen yellow, with black spots on the sides and top, the extremity being white. All the wings are white, with black spots, whose number is very variable; but, on the anterior edges of each anterior wing, are placed five, and on the external edges, six.
Under Side. The legs are black and white, the thighs yellow; the abdomen white, spotted with black. All the wings are white, with black spots, most of which, observed on the upper side, being seen on this.
This species is closely allied to the common British species, Spilosoma lubricepida, and Menthrastri; but is of larger size, the spots being also larger. The two figures given by Drury, are now ascertained to be the sexes of the same species, as, indeed, our author had surmised might be the case. It appears to be a very common species, and is stated by Drury to breed twice a year, namely, in June and September. The caterpillar is very hairy, and when young is white; as it advances in age, it acquires a fox colour, and, in its last skin, becomes almost black. Dr. Thaddeus W. Harris, a distinguished American entomologist, to whom I am indebted for many valuable insects of that country, has published a very interesting notice, in the work above cited, upon this insect, under the title of "The Natural History of the Salt-marsh Caterpillar," under which name the larva of this insect is commonly known, and which is exceedingly destructive to grasses of various kinds. He states, that when nearly full-fed, "they become very voracious, and continue eating all the day and night without intermission. Soon they leave the meadows, aggregated in great numbers, and commence the wandering state, or begin to run, as is the phrase, devouring everything in their progress; corn-fields, gardens, and even the coarse and rank produce of road sides, afford them temporary nourishment, until they have found a place of security from the wind and weather." Dr. Harris, in a communication to me, has stated, that he had ascertained that this insect was the Acria of Fabricius, and that Professor Peck's name must, therefore, be rejected. Abbot observes, respecting this caterpillar, that it is "a general devourer of all field and garden-plants, and weeds. It spun up in a thin web, intermixed with its own hairs, on the 16th of May, and the moth came out on the 2d of June. Others of the autumnal brood, taken in September, spun up on the 18th of that month, and remained in the chrysalis until the 21st of April."
PLATE IV.
