THE LEPIDOPTERA 231 



In some cases the maxillary palpus is developed : in others it is nearly 

 or wholly lacking. The labium or hinder lip is also practically absent 

 except for the labial palpi which are usually large, thickly covered by 

 hairs or scales, and project forward at the sides of the head, often 

 turning upward somewhat, and partially or wholly concealing the pro- 

 boscis when this is coiled up under the head, the place where it is carried 

 when not in use. 



The mouth parts of the larva (or caterpillar as it is usually called) 

 are entirely different. In this stage they are chewing structures, similar 

 to those of a grasshopper in a general way, and no special description is 

 needed. ' In the center of the end of the labium, however, is a slender 

 projection called the spinneret, which at its tip has the external opening 

 of the duct leading to the silk glands. 



The antennae of adult Lepidoptera are usually quite long but vary 

 greatly in their form in different species. In the butterflies they are 

 slender but enlarged near the tip forming a club (Figs. 309 to 317), or 

 with this enlarged part bent into a sort of hook (Fig. 308) . These forms 

 of antennae are almost never found in the moths, where they may be 

 simple and thread-like; with small hair-like projections at the side; 

 bristles in place of the hairs; clusters of the bristles; with tooth-like or 

 saw-like side projections; with long projections on one or both sides, in 

 the latter case giving the antennae a feather-like appearance; and other 

 forms also occur. (Compare Figs. 228 to 305). 



The eyes are large, though in some cases partly concealed by hairs 

 or scales, which as a rule thickly clothe the entire body. Ocelli are also 

 sometimes present. On the top of the prothorax a pair of projections or 

 lobes often occurs, called patagiae, sometimes very large and capable of 

 some movement; in others, smaller or even reduced to mere traces. On 

 the large mesothorax is a somewhat similar pair of structures called the 

 tegulae which extend backward over the point where each fore wing 

 articulates with the body. The abdomen may be long or short, stout 

 or slender, connected with the thorax either by a broad or a rather 

 constricted attachment. The legs are quite long and slender. 



Characters by which the members of this group may be distinguished 

 are: 



Insects which as adults have (with a few exceptions) four membranous 

 wings more or less completely covered by overlapping scales: mouth parts 

 for sucking. The larvae have chewing mouth parts. Metamorphosis 

 complete. 



The Lepidoptera is such a large order that great differences in its 

 members are very common. The smallest ones are almost microscopic 

 while the largest one known may measure about a foot between the tips 

 of its expanded wings. The wings of each side, to obtain their greatest 

 efficiency, are more or less completely coordinated for flight by one 



