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NYMPHALIDÆ (THE BRUSH-FOOTED BUTTERFLIES)
ОглавлениеThe family of the Nymphalidæ is composed of butterflies which are of medium and large size, though a few of the genera are made up of species which are quite small. They may be distinguished from all other butterflies by the fact that the first pair of legs in both sexes is atrophied or greatly reduced in size, so that they cannot be used in walking, but are carried folded up upon the breast. The fore feet, except in the case of the female of the snout-butterflies (Libytheinæ), are without tarsal claws, and hence the name "Brush-footed Butterflies" has been applied to them. As the anterior pair of legs is apparently useless, they have been called "The Four-footed Butterflies," which is scientifically a misnomer.
Egg.—The eggs of the Nymphalidæ, for the most part, are dome-shaped or globular, and are marked with raised longitudinal lines extending from the summit toward the base over the entire surface or over the upper portion of the egg. Between these elevations are often found finer and less elevated cross-lines. In a few genera the surface of the eggs is covered with reticulation arranged in geometrical patterns (see Fig. 1).
Caterpillar.—The caterpillars of the Nymphalidæ, as they emerge from the egg, have heads the diameter of which is larger than that of the body, and covered with a number of wart-like elevations from which hairs arise. The body of the immature larva generally tapers from before backward (see Plate III, Figs. 7 and 11). The mature larva is cylindrical in form, sometimes, as in the Satyrinæ, thicker in the middle. Often one or more of the segments are greatly swollen in whole or in part. The larvæ are generally ornamented with fleshy projections or branching spines.
Chrysalids.—The chrysalids are for the most part angular, and often have strongly marked projections. As a rule, they hang with the head downward, having the cremaster, or anal hook, attached to a button of silk woven to the under surface of a limb of a tree, a stone, or some other projecting surface. A few boreal species construct loose coverings of threads of silk at the roots of grasses, and here undergo their transformations. The chrysalids are frequently ornamented with golden or silvery spots.
This is the largest of all the families of butterflies, and it is also the most widely distributed. It is represented by species which have their abode in the cold regions of the far North and upon the lofty summits of mountains, where summer reigns for but a few weeks during the year; and it is enormously developed in equatorial lands, including here some of the most gloriously colored species in the butterfly world. But although these insects appear to have attained their most superb development in the tropics, they are more numerous in the temperate regions than other butterflies, and a certain fearlessness, and fondness for the haunts of men, which seems to characterize some of them, has brought them more under the eyes of observers. The literature of poetry and prose which takes account of the life of the butterfly has mainly dealt with forms belonging to this great assemblage of species.
In the classification of the brush-footed butterflies various subdivisions have been suggested by learned authors, but the species found in the United States and the countries lying northward upon the continent may be all included in the following six groups, or subfamilies:
1. The Euplœinœ, the Euplœids. 2. The Ithomiinœ, the Ithomiids. 3. The Heliconiinœ, the Heliconians. 4. The Nymphalinœ, the Nymphs. 5. The Satyrinœ, the Satyrs. 6. The Libytheinœ, the Snout-butterflies.
The insects belonging to these different subfamilies may be distinguished by the help of the following analytical table, which is based upon that of Professor Comstock, given in his "Manual for the Study of Insects" (p. 396), which in turn is based upon that of Dr. Scudder, in "The Butterflies of New England" (vol. i, p. 115).
Key to the subfamilies of the Nymphalidæ of the United States and Canada
I. With the veins of the fore wings not greatly swollen at the base.
A. Antennæ naked.
(a) Fore wings less than twice as long as broad—Euplœinœ.
(b) Fore wings twice as long as broad and often translucent, the abdomen
extending far beyond the inner margin of the hind wings—Ithomiinœ.
B. Antennæ clothed with scales, at least above.
(a) Fore wings at least twice as long as broad—Heliconiinœ.
(b) Fore wings less than twice as long as broad.
1. Palpi not as long as the thorax—Nymphalinœ.
2. Palpi much longer than the thorax—Libytheinœ.
II. With some of the veins of the fore wings greatly swollen at the base—Satyrinœ.
We now proceed to present the various genera and species of this family which occur within the territorial limits of which this book treats. The reader will do well to accompany the study of the descriptions, which are at most mere sketches, by a careful examination of the figures in the plates. In this way a very clear idea of the different species can in most instances be obtained. But with the study of the book should always go, if possible, the study of the living things themselves. Knowledge of nature founded upon books is at best second-hand. To the fields and the woods, then, net in hand! Splendid as may be the sight of a great collection of butterflies from all parts of the world, their wings
"Gleaming with purple and gold,"
no vision is so exquisite and so inspiring as that which greets the true aurelian as in shady dell or upon sun-lit upland, with the blue sky above him and the flowers all around him, he pursues his pleasant, self-imposed tasks, drinking in health at every step.