_Egg._--The egg is ovate conical, ribbed perpendicularly with many raised cross-lines between the ridges. The eggs are pale green in color.
_Caterpillar._--The caterpillar is cylindrical, fleshy, transversely wrinkled, and has on the second thoracic and eighth abdominal segment pairs of very long and slender fleshy filaments; the body is ornamented by dark bands upon a greenish-yellow ground-color; the filaments are black.
_Chrysalis._--The chrysalis is stout, cylindrical, rapidly tapering on the abdomen, and is suspended from a b.u.t.ton of silk by a long cremaster.
The color of the chrysalis is pale green, ornamented with golden spots.
The larvae of the genus _Anosia_ feed for the most part upon the varieties of milkweed (_Asclepias_), and they are therefore called "milkweed b.u.t.terflies." There are two species of the genus found in our fauna, one, _Anosia plexippus_, Linnaeus, which is distributed over the entire continent as far north as southern Canada, and the other, _Anosia berenice_, Cramer, which is confined to the extreme southwestern portions of the United States, being found in Texas and Arizona.
(1) =Anosia plexippus=, Linnaeus, Plate VII, Fig. 1, ? (The Monarch).
_b.u.t.terfly._--The upper surface of the wings of this b.u.t.terfly is bright reddish, with the borders and veins broadly black, with two rows of white spots on the outer borders and two rows of pale spots of moderately large size across the apex of the fore wings. The males have the wings less broadly bordered with black than the females, and on the first median nervule of the hind wings there is a black scent-pouch.
_Egg._--The egg is ovate conical, and is well represented in Fig. 4 in the introductory chapter of this book.
_Caterpillar._--The caterpillar is bright yellow or greenish-yellow, banded with shining black, and furnished with black fleshy thread-like appendages before and behind. It likewise is well delineated in Fig. 16, as well as in Plate III, Fig. 5.
_Chrysalis._--The chrysalis is about an inch in length, pale green, spotted with gold (see Fig. 24, and Plate IV, Figs. 1-3).
The b.u.t.terfly is believed to be polygoneutic, that is to say, many broods are produced annually; and it is believed by writers that with the advent of cold weather these b.u.t.terflies migrate to the South, the chrysalids and caterpillars which may be undeveloped at the time of the frosts are destroyed, and that when these insects reappear, as they do every summer, they represent a wave of migration coming northward from the warmer regions of the Gulf States. It is not believed that any of them hibernate in any stage of their existence. This insect sometimes appears in great swarms on the eastern and southern coasts of New Jersey in late autumn. The swarms pressing southward are arrested by the ocean. The writer has seen stunted trees on the New Jersey coast in the middle of October, when the foliage has already fallen, so completely covered with clinging ma.s.ses of these b.u.t.terflies as to present the appearance of trees in full leaf (Fig. 79).
[Ill.u.s.tration FIG. 79.--Swarms of milkweed b.u.t.terflies 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 b.u.t.terfly 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 b.u.t.terflies 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 b.u.t.terfly 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 Euploeinae 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 ill.u.s.trated 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 s.e.x 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 ITHOMIINae (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 b.u.t.terflies."--PLINY, PHILEMON HOLLAND"S Translation.
_b.u.t.terfly._--This subfamily is composed for the most part of species of moderate size, though a few are quite large. The fore wings are invariably greatly lengthened and are generally at least twice as long as broad. The hind wings are relatively small, rounded, and without tails. The wings in many of the genera are transparent. The extremity of the abdomen in both s.e.xes extends far beyond the margin of the hind wings, but in the female not so much as in the male. The antennae are not clothed with scales, and are very long and slender, with the club also long and slender, gradually thickening to the tip, which is often drooping. The fore legs are greatly atrophied in the males, the tibia and tarsi in this s.e.x being reduced to a minute k.n.o.b-like appendage, but being more strongly developed in the females.
The life-history of none of the species reputed to be found in our fauna has been carefully worked out. The larvae are smooth, covered in most genera with longitudinal rows of conical prominences.
The chrysalids are said to show a likeness to those of the Euploeinae, being short, thick, and marked with golden spots. Some authors are inclined to view this subfamily as merely const.i.tuting a section of the Euploeinae. The insects are, however, so widely unlike the true Euploeinae that it seems well to keep them separate in our system of cla.s.sification. In appearance they approach the Heliconians more nearly than the Euploeids. Ithomiid b.u.t.terflies swarm in the tropics of the New World, and several hundreds of species are known to inhabit the hot lands of Central and South America. But one genus is found in the Old World, _Hamadryas_, confined to the Australian region. They are protected like the Euploeids and the Heliconians. In flight they are said to somewhat resemble the dragon-flies of the genus _Agrion_, their narrow wings, greatly elongated bodies, and slow, flitting motion recalling these insects, which are known by schoolboys as "darning-needles."
Three genera are said to be represented in the extreme southwestern portion of the United States. I myself have never received specimens of any of them which indisputably came from localities within our limits, and no such specimens are found in the great collection of Mr. W.H.
Edwards, which is now in my possession. A paratype of Reakirt"s species, _Mechanitis californica_, is contained in the collection of Theodore L.
Mead, which I also possess. Mr. Mead obtained it from Herman Strecker of Reading, Pennsylvania. Reakirt gives Los Angeles as the locality from which his type came; but whether he was right in this is open to question, inasmuch, so far as is known, the species has not been found in that neighborhood since described by Reakirt.
Genus MECHANITIS, Fabricius
_b.u.t.terfly._--b.u.t.terflies of moderate size, with the fore wings greatly produced, the inner margin bowed out just beyond the base, and deeply excavated between this projection and the inner angle. The lower discocellular vein in the hind wings is apparently continuous with the median vein, and the lower radial vein being parallel with the median nervules, the median vein has in consequence the appearance of being four-branched. The submedian vein of the fore wings is forked at the base. The costal margin of the hind wings is clothed with tufted erect hairs in the male s.e.x. The fore legs of the male are greatly atrophied, the tarsi and the tibia being fused and reduced to a small k.n.o.b-like appendage. The fore legs of the female are also greatly reduced, but the tarsi and tibia are still recognizable as slender, thread-like organs.
[Ill.u.s.tration FIG. 80.--Neuration of the genus _Mechanitis_. The letters refer to the names of the veins. (See Fig 40.)] The caterpillars are smooth, cylindrical, ornamented with rows of short fleshy projections.
The chrysalids are short and stout, suspended, and marked with golden spots.
There are numerous species belonging to this genus, all natives of tropical America. The only species said to be found within the limits of the United States occurs, if at all, in southern California. It is, however, probably only found in the lower peninsula of California, which is Mexican territory. No examples from Upper California are known to the writer.
(1) =Mechanitis californica=, Reakirt, Plate VIII, Fig. 2, ? (The Californian Long-wing).
The original description given by Reakirt in the "Proceedings of the Entomological Society of Philadelphia," vol. v, p. 223, is as follows:
"Expanse, 2.45-2.56 inches. Fore wing above, brownish-black; a basal streak over the median nervure, and two rounded spots near the inner angle, orange-tawny; of these the outer is the largest, sometimes the inner is yellow, and sometimes both are nearly obsolete; a spot across the cell near its termination, much narrower than in _M. isthmia_, and in one example reduced to a mere dot on the median nervure; a more or less interrupted belt across the wing from the costa to near the middle of the outer margin, and an oblong subapical spot, yellow; in the specimen just mentioned there is an additional yellow spot below the medio-central veinlet.
"Beneath the same, suffused with orange-tawny at the base and the inner angle, with a row of eight or nine submarginal white spots along the outer margin.
"Hind wing above, orange-tawny, with a broad mesial band, entire, and a narrow outer border, from the middle of the costa to the a.n.a.l angle, brownish-black.
"Beneath the same, a yellow spot on the root of the wing; a band runs along the subcostal nervure from the base to the margin, where it is somewhat dilated; immediately below its termination, a mark in the form of an irregular figure 2, usually with the upper part inordinately enlarged; between this and the base, on the central line of the band above, three small subtriangular spots; all these markings blackish-brown; a submarginal row of seven white spots on the outer margin.
"Body brownish; wing-lappets and thorax spotted with tawny-orange; antennae yellowish, with the base dusky.
"_Hab._--Los Angeles, California."
The species is probably only a local race of the insect known to naturalists as _M. polymnia_, Linnaeus, as Reakirt himself admits. The figure in the plate is from one of Reakirt"s paratypes.
Genus CERATINIA, Fabricius
_b.u.t.terfly._--b.u.t.terflies of medium size, very closely related in structure to the b.u.t.terflies of the genus _Mechanitis_. The peculiarity of this genus, by which it may be distinguished from others belonging to this subfamily, is the fact that the _lower_ discocellular vein in the hind wing of the male s.e.x is strongly in angled, while in the genus _Mechanitis_ it is the _middle_ discocellular vein of the hind wing which is bent inwardly.
_Early Stages._--Unknown for the most part.
There are at least fifty species belonging to this genus found in the tropical regions of America; only one is said to occur occasionally within the limits of the region covered by this volume.
[Ill.u.s.tration FIG. 81.--Neuration of the genus _Ceratinia_. (For explanation of lettering, see Fig. 40.)]
(1) =Ceratinia lycaste=, Fabricius, Plate VIII, Fig. 3, ? (Lycaste).
_b.u.t.terfly._--The b.u.t.terfly is rather small, wings semi-transparent, especially at the apex of the fore wings. The ground-color is pale reddish-orange, with the border black. There are a few irregular black spots on the discal area of the fore wings, and a row of minute white spots on the outer border. There is a black band on the middle of the hind wings, curved to correspond somewhat with the outline of the outer border. The markings on the under side are paler. The variety _negreta_, which is represented in the plate, has a small black spot at the end of the cell of the hind wings, replacing the black band in the form common upon the Isthmus of Panama.
+--------------------------------------------------------------+ | | | EXPLANATION OF PLATE VIII | | | | | | 1. _Dircenna klugi_, Hubner, ?. | | 2. _Mechanitis californica_, Reakirt, ?. | | 3. _Ceratinia lycaste_, Fabricius, ?. | | 4. _Coloenis delila_, Fabricius, ?. | | 5. _Heliconius charitonius_, Linnaeus, ?. | | 6. _Coloenis julia, Fabricius_, ?. | | 7. _Dione vanillae_, Linnaeus, ?. | | 8. _Euptoieta hegesia_, Cramer, ?. | | 9. _Euptoieta claudia_, Cramer, ?. | | | | | | [Ill.u.s.tration PLATE VIII.] | +--------------------------------------------------------------+