Part 15

Large butterflies, our species being one of the smallest of the genus. Palpi produced, heavily scaled, rising above the head. Fore wings excavated on the outer margin; costal and median veins stout; upper discocellular vein wanting, and lower discocellular feeble or lacking. Hind wings somewhat crenulate on the outer margin, the cell, which is relatively quite small, being feebly closed by an attenuated veinlet.

The genus, which is quite large, reaches its greatest development in the tropics of the Old World, and there is only one species in the western hemisphere, which may have been introduced in the old days of the slave trade. Most of the species are mimics and the strange thing is that the mimicking form is generally the female, which has the color and markings of some one or other of the milkweed butterflies of the African and oriental tropics. The female of our species patterns after the markings of Danais chrysippus, a common milkweed butterfly of Africa. This adaptation of species to the form and color of “protected” insects is of course not conscious. It is the result of a long evolution in past ages.

(1) Hypolimnas misippus (Linnæus), Plate XLII, ♂; Plate XLIII, ♀ (The Mimic).

Occurs in Florida, the Antilles, and northern South America. While very abundant in Africa, it seems to be scarce in the New World. The female differs greatly from the male on the upper side of the wings, but resembles that sex on the lower side. Expanse ♂, 2.50 inches; ♀ 3.00 inches.

GENUS BASILARCHIA SCUDDER

(THE WHITE ADMIRALS).

Rather large butterflies. Fore wings subtriangular, rounded at the apex, and lightly excavated on the lower two thirds of the outer margin. Hind wings rounded, somewhat crenulate. Egg nearly spherical (see Plate C, Fig. f) pitted with large hexagonal cells. The caterpillar in its mature state cylindrical, with the second segment adorned with two prominent club-shaped tubercles, and the fifth, ninth, and tenth segments also having raised tubercles (see Plate C, Fig. h). They feed upon oaks, birches, willows, and lindens, preferably the two latter. The caterpillars after hatching hibernate in little winter quarters, which they make out of the fragment of a small leaf, which they tie together with silken threads, and also secure to the twig by a few strands. The chrysalis has a projecting boss on the back; the head is either rounded or slightly bifid.

There are a number of species in the United States, several of which mimic other butterflies in a singular manner, B. disippus closely resembling Anosia plexippus. The caterpillars do not pupate until summer has come; the butterflies take wing when the lindens bloom.

(1) Basilarchia astyanax (Fabricius), Plate XLIV, ♀ (The Red-spotted Purple).

Our figure gives a good idea of the upper side of the wings. On the lower side the wings are brown, banded with black on the margins, the inner row of marginal spots being red, with two red spots at the base of the fore wings, and four such spots at the base of the hind wings. Palpi white below; a white stripe along the sides of the abdomen. Expanse 3.00-3.25 inches. The egg and caterpillar are shown on Plate C. The caterpillar is found on a variety of plants, but most commonly on lindens, willows, and wild cherry trees.

Found all over the United States and Canada, as far west as the Rocky Mountains, but not in the very hot lowlands of the Gulf region. Is said to occur on the uplands of Mexico.

Between B. astyanax and the following species, B. arthemis, there is more or less affinity. They represent two lines of evolution from a common ancestry, and there are evidences of atavic reversion to type constantly occurring in both forms. They even occasionally interbreed with each other, and hybrids are not altogether uncommon. The whole genus in fact is in a more or less plastic state, and well deserves the careful attention of biologists.

(2) Basilarchia arthemis (Drury), Plate XLV, ♂ (The Banded Purple).

Our figure shows the upper side of the form which is most usual. It will be seen that there are red spots on the hind wings behind the white band. There is a variety called proserpina in which the white band becomes very narrow and the red spots almost or entirely disappear. When the white band and the red spots wholly disappear, as they sometimes do, it is almost impossible to distinguish this species from B. astyanax. Expanse 2.50-2.75 inches. The egg has “kite-shaped” cells. The caterpillar feeds on willows, hawthorns, and wild apple and plum trees.

Found in Canada, New England, and southward in Pennsylvania upon the higher ranges of the mountains. It is a northern form. It has not thus far been recorded from the western half of the continent, where it is replaced by a somewhat similarly marked, but larger, species, known as B. Weidemeyeri. The latter insect is found as far east as western Nebraska and Colorado. I have taken it very frequently in Wyoming about Laramie Peak, where it seems to be a common insect in the wooded canyons.

(3) Basilarchia disippus (Godart), Plate XLVI, ♂; Plate C, Fig. f, egg; Fig. h, larva. (The Viceroy).

Mimics Anosia plexippus. Range from Canada to the Gulf.

This is one of the most striking cases of mimicry which occurs in our fauna.

(4) Basilarchia lorquini (Boisduval), Plate XLVII, ♂ (Lorquin’s Admiral).

Easily distinguished by white bar at end of cell of fore wing and red spot at apex. Expanse 2.25-2.75 inches.

GENUS ADELPHA HÜBNER (THE SISTERS).

Cell of fore wing lightly closed, of hind wing open; outer margin of wings rarely excavated. The chrysalids have peculiar forms, having bifid heads and broad wing-cases; marked with metallic spots on a brown ground.

There are many species in tropical America, some of which are very showy; only one occurs within our limits.

(1) Adelpha californica Butler, Plate XLVIII, ♂ (The Californian Sister).

The insect, well displayed in our figure, has an expanse of from 2.50-3.00 inches. The caterpillar feeds upon oaks. The range is through southern California, Nevada, southern Utah, Arizona, and Mexico.

GENUS CHLORIPPE BOISDUVAL

(THE EMPEROR BUTTERFLIES).

Small butterflies generally of some shade of fulvous, with a submarginal row of eye-like spots on the hind wings, and in a few species with a similar spot on the fore wings. The apex of the fore wing is somewhat truncated and the lower two thirds is slightly excavated. Hind wings somewhat elongated posteriorly at the anal angle. Outer margins more or less crenulate. Eggs nearly globular, broad on top, ornamented with eighteen to twenty broad, but low, vertical ribs, between which are delicate crosslines; laid in clusters. Head of caterpillar squarish, crowned by two diverging spines on which are many little spinules. Back of the head there is a frill of spines. Body thickest at the middle, tapering fore and aft. Hind pair of pro-legs long and diverging. They feed upon hackberry trees (Celtis). The chrysalis has a very remarkable arrangement of the cremaster, which is disk-like, studded with hooks; the whole so arranged that the pupa, when suspended, hangs with the ventral or belly side parallel to the supporting surface.