“The chrysalis seems unable to bend the body toward the back or toward the wing covers; sidewise, however, it can turn until the body is extended nearly parallel to the horizontal surface from which it is suspended. Six chrysalids which hung in a north window in September, 1919, and which I observed for fourteen days, were noted to be invariably and unanimously pointed inward (toward the warm room, that is) every morning. During the warmer part of the day there was no uniformity in position. Six specimens—fourteen days; it appears to be more, perhaps, than mere coincidence. The pupal sensibility to light and temperature stimulii should be worth investigation.”
THE APPEARANCE OF THE BUTTERFLY
“Two or three weeks after pupation (the period varies with the temperature, from eight days in August to twenty-seven in November) the chrysalis turns nearly black, and a diagonal fissure appears on either side, extending from the back of the head down along the antenna cases, nearly to the middle ventrum.
“About twelve hours later, after some little wriggling, the ventral triangle formed by the covering of the head, antennae and mouth parts falls open trap-door fashion, the antennae covers serving as hinges and the flexing point being about one-third of the distance up the wing covers from the abdomen. There is also a dorsal cleavage following the medial dorsum to the first abdominal segment, then the outline of the wing covers to a point half way to the end of the antenna covers. The crumpled-winged imago wriggles out and mounts the empty shell, to which it clings by the four hinder limbs, turning the entire body back and forth as if mounted on a pivot. In each of these turns the body describes an arc of nearly 90 degrees, the body being held stiff. The angle of the body is about 45 degrees from the vertical, the head being uppermost. The proboscis is usually partially unrolled. In five or six hours the soft, wrinkled wings spread and harden, and the insect is able to fly. A thin, transparent liquid, and sometimes a thick, reddish substance, are voided by the newly emerged butterfly.”
CHAPTER V
THE CLASSIFICATION OF BUTTERFLIES
In every science it is necessary to manipulate a large number of related facts, and this cannot be done unless the data are arranged in some systematic and orderly fashion. In order to make use of the facts about butterflies, one must know something of the relation of one butterfly to another, and the relation of butterflies in general to the rest of the animal kingdom.
SUBKINGDOMS, CLASSES, ORDERS, AND SUBORDERS
Members of the animal kingdom which have no spinal column, but only an external skeleton composed of horny rings, are assigned to the subkingdom Arthropoda. Arthropods which have six legs are grouped together in the class Insecta. Insects with scales on their wings are assigned to the order called Lepidoptera. This order is divided into two suborders, the Rhopalocera or butterflies and the Heterocera or moths. Butterflies fly in the daytime, and have slender antennae with club-like knobs at the ends; moths are usually nocturnal or crepuscular, and their antennae are not knobbed, but are thread-like, feather-like, or hooked at the extremity.