INTRODUCTORY

THE PLACE OF BUTTERFLIES IN THE ANIMAL KINGDOM

The Animal Kingdom is divided into various subkingdoms. One of these is the subkingdom of the Arthropoda. This word is derived from the Greek nouns ἄρθρον (arthron) meaning joint, and πούς (pous) meaning foot. The Arthropoda are animals the bodies of which are made up of a series of rings or segments jointed together, and the other organs of which are likewise composed of tubular bodies similarly united. All arthropods are invertebrates; that is to say, they do not have backbones and internal skeletons, such as are possessed by fishes, reptiles, birds, and mammals, including man. Vertebrate animals have endoskeletons, “inside skeletons.” In a ham, for instance, the bone is internal to the muscular parts, or meat, and lies near the middle. The muscles of a man clothe his bones. In the arthropods, on the contrary, the hard parts clothe the muscles. Arthropods are therefore said to have exoskeletons, “outside skeletons.” The body, the legs, and other organs of an insect or a crab consist of a series of hollow tubes held together by flexible skin at the points of union, and controlled in their movements by muscles which pull from the inside. The meat of a lobster is inside of the shell, or exoskeleton, as everybody who has eaten a lobster knows. The arrangement is exactly the reverse of that which we find in the vertebrates.

EXPLANATION OF PLATE A

Fig. a.	Magnified scales of butterflies. 1, ordinary scale of Papilio; 2, do. of Colias; 3 androconium, or scale from wing of male Neonympha eurytus; 4, do. of male Pieris oleracea; 5, do. of male Lycæna pseudargiolus (Figs. 1-2 after Verity; Figs. 3-5 after Scudder).
Fig. b.	Patch of scales on wing of Pieris napi (after Verity).
Fig. c.	Body of Anosia plexippus.
	I.	Head. 1, antenna; 2, eye; 3, proboscis; 4, palpus; cl. clypeus; o, occiput.
	II.	Thorax. 5, prothoracic leg; 6, mesothoracic leg; 7, metathoracic leg; e, e, e,episterna; c, c, c, coxæ; tr., tr., trochanters of last two legs; f, f, femora of do.; s, s, s, scuta of first, second, and third segments of thorax.
	III.	Abdomen. 1-9 segments; sp., sp., spiracles (after Burgess).
Fig. d.	Head and legs of Œneis semidea, showing aborted front leg.
Fig. e.	Palpus of Argynnis aphrodite.
Fig. f.	Leg of Argynnis idalia. 1, coxa; 2, trochanter; 3, femur; 4, tibia; 5, tarsus.
Fig. g.	Knobbed antenna of Argynnis idalia.
Fig. h.	Clubbed antenna of Basilarchia astyanax.
Fig. i.	Hooked antenna of Amblyscirtes vialis.

Plate A

The subkingdom of the Arthropoda is divided into six classes, one of which consists of the Insecta (insects). It is estimated that there are three and a half millions of species of insects upon the globe, not to speak of the vast number of species which are now extinct, and known only by their fossil remains.

The Class Insecta is subdivided into many Orders. To attempt even to briefly speak of all these orders would take more space than the publisher has allotted to the author, and it is enough to say that butterflies belong to the order Lepidoptera. The lepidoptera are divided into two Suborders: the Rhopalocera, or Butterflies, and the Heterocera, or Moths. Both are characterized by having scaly wings, hence the name, which is derived from the Greek words λεπὶς (lepis) meaning scale, and πτερὸν (pteron) meaning wing. Lepidoptera are “scale-winged insects.” Any one who has ever handled a butterfly or moth, must have noticed upon his fingers a dust-like substance, rubbed off from the wings of the captured insect. Upon examining this substance under a microscope it is seen to be composed of minute scales (see [Plate A], Fig. a), and upon looking at the wing of a butterfly under a magnifying glass it is seen to be covered with such scales, arranged somewhat as the scales upon the sides of a fish, or as the shingles upon the roof of a house (see [Plate A], Fig. b).

Butterflies are mainly diurnal in their habits, preferring the sunshine. Moths on the other hand are nocturnal, and fly in the dusk, or after dark. Butterflies are therefore often called diurnal lepidoptera, and moths are spoken of as nocturnal lepidoptera. There are, however, a few butterflies which fly at dusk, and there are many moths which are diurnal in their habits. Such moths are generally gay in color, and for the most part inhabit tropical countries, although we have a few such species in the United States. Ordinarily the best way to distinguish between butterflies and moths is by examining their antennæ, or “feelers,” as they are sometimes incorrectly called. In the case of butterflies the antennæ are thread-like, terminating in a small knob-like, or club-like enlargement. It is this fact which has led naturalists to call them Rhopalocera. The word is derived from the Greek nouns ῥώπαλον (rhopalon) meaning a club, and κέρας (keras) a horn. Butterflies are lepidoptera having at the end of their antennæ clubs, which are sometimes short, long, or hooked (see [Plate A], Figs. g, h, i.) The forms assumed by the antennæ of moths are very various. The moths are therefore known as Heterocera, the word being compounded from the Greek adjective ἕτερος ( all sorts) and the noun κέρας (keras) a horn. Moths are lepidoptera having all sorts of antennæ, except such as are club-shaped at their ends. However there is no rule without its exceptions, and there are a few rare moths in tropical lands which have club-shaped antennæ like butterflies, but none of these occur in the region with which this book deals.