[a]Fig. 79.]—Swarms of milkweed butterflies resting on a tree. Photographed at night by Professor C.F. Nachtrieb. (From "Insect Life," vol. v, p. 206, by special permission of the United States Department of Agriculture.)
This butterfly is a great migrant, and within quite recent years, with Yankee instinct, has crossed the Pacific, probably on merchant vessels, the chrysalids being possibly concealed in bales of hay, and has found lodgment in Australia, where it has greatly multiplied in the warmer parts of the Island Continent, and has thence spread northward and westward, until in its migrations it has reached Java and Sumatra, and long ago took possession of the Philippines. Moving eastward on the lines of travel, it has established a more or less precarious foothold for itself in southern England, as many as two or three dozen of these butterflies having been taken in a single year in the United Kingdom. It is well established at the Cape Verde Islands, and in a short time we may expect to hear of it as having taken possession of the continent of Africa, in which the family of plants upon which the caterpillars feed is well represented.
(2) Anosia berenice, Cramer, Plate VII, Fig. 2, ♂ (The Queen).
This butterfly is smaller than the Monarch, and the ground-color of the wings is a livid brown. The markings are somewhat similar to those in A. plexippus, but the black borders of the hind wings are relatively wider, and the light spots on the apex of the fore wings are whiter and differently located, as may be learned from the figures given in Plate VII.
There is a variety of this species, which has been called Anosia strigosa by H.W. Bates (Plate VII, Fig. 3, ♂), which differs only in that on the upper surface of the hind wings the veins as far as the black outer margin are narrowly edged with grayish-white, giving them a streaked appearance. This insect is found in Texas, Arizona, and southern New Mexico.
All of the Euplœinæ are "protected" insects, being by nature provided with secretions which are distasteful to birds and predaceous insects. These acrid secretions are probably due to the character of the plants upon which the caterpillars feed, for many of them eat plants which are more or less rank, and some of them even poisonous to the higher orders of animals. Enjoying on this account immunity from attack, they have all, in the process of time, been mimicked by species in other genera which have not the same immunity. This protective resemblance is well illustrated in Plate VII. The three upper figures in the plate represent, as we have seen, species of the genus Anosia; the two lower figures represent two species of the genus Basilarchia. Fig. 4 is the male of B. disippus, a very common species in the northern United States, which mimicks the Monarch. Fig. 5 represents the same sex of B. hulstii, a species which is found in Arizona, and there flies in company with the Queen, and its variety, A. strigosa, which latter it more nearly resembles.
SUBFAMILY ITHOMIINÆ (THE LONG-WINGS)
"There be Insects with little hornes proaking out before their eyes, but weak and tender they be, and good for nothing; as the Butterflies."—Pliny, Philemon Holland's Translation.