X INTRODUCTION. 



hind tibiae. The front legs are rudimentarj- in manj- butterflies and much smaller than the 

 others. In moths the hind legs are sometimes imperfectly developed. 



The respiratory system consists of spiracles or respiratory pores, situated on the sides 

 of the thorax and abdomen, but not more than a single pair on each segment. These are 

 connected with the tracheae, or air tubes, which subdivide and supply all parts of the body. 



The heart is a tubular organ, extending from near the caudal extremity, through the 

 abdomen and thorax, to the head. It consists of a series of chambers, communicating with 

 one another by means of valves, and also at the sides with the cavity of the body. Here 

 there are valves also. The blood, which is a colourless fluid, is driven by the action of the 

 valves from all parts of the body, the alimentary canal and the inter-muscular spaces, towards 

 the head, whence it escapes into the cavity of the body. 



The nervous system consists of a dorsal ganglion in the head and a series of ventral 

 ganglia in the body connected by two cords. From these ganglia the nerves pass out to the 

 different parts of the body. 



The alimentary canal of Lepidoptera comprises a mouth, pharynx, aesophagus, sucking 

 stomach, proventriculus or gizzard, ventriculus or true stomach, and the intestine, which is 

 subdivided into ileum, colon and rectum. 



The urinary organs consist of six long tubes which open into the posterior end of the 

 stomach by two excretory ducts. 



The reproductive organs are formed of a set of tubes on each side of the body, opening 

 by a common orifice near the end of the abdomen. 



The muscles, which are colourless, transparent or yellowish white, and of soft and almost 

 gelatinous consistency, are very numerous. Examined under the microscope, they are seen 

 to be striated, like the voluntary muscles of higher animals. 



Fat is present in the bodies of insects, usuallj- in large quantity, especially about the 

 alimentary canal and at the sides of the body. 



DEVEL OPMENT. 



In the early stages Lepidoptera pass through the various forms of &gg, larva or cater- 

 pillar and pupa or chrysalis. 



The eggs are of various forms, being round, oval, cylindrical, lenticular, or cup-shaped, 

 and their surface may be smooth, ribbed, or granulated. They are usually unicolorous, white, 

 green, bluish, brown or black, rarely banded or spotted. The eggs are usually attached by 

 a sticky gum-like material to the food-plant of the future caterpillar, and are arranged in 

 irregular masses, straight rows in a ring round a twig or singly. Most of them are uncovered, 

 but some are covered with hair or wool from the body of the female. 



The larva is worm-shaped and consists of thirteen divisions, the first of which is the 

 head, the next three the thoracic segments and the remainder the abdominal segments. The 

 head is horny, and its upper and anterior surface consists of a horny plate which is divided 

 by a longitudinal furrow. The shape of the head varies: it may be round, triangular, or heart- 

 shaped, and sometimes with a pyramidal projection, or furnished with spines. The mouth organs 

 are horny and consist of a labrum, or upper lip, two pincer-shaped mandibles or upper jaws, a 

 jointed maxilla or lower jaw, and a labium or lower lip. The maxilla and often the labium 

 are provided with small palpi. On the labium there is also a remarkable organ, the so-called 

 spinneret, which is a tube composed of alternate horny and membranous longitudinal pieces, 

 which discharges the sticky substance required to form the skin of the pupa and which is 

 secreted by two glandular organs. The eyes of the larva) are simple and arc almost always 

 present ; there are usually six on each side, varying in size and arranged in a circle. The 

 three thoracic segments are distinguished from the abdominal segments by the different 

 character of the legs. The legs of caterpillars are divided into true or thoracic legs, and 



