494 ARTHROPODA. 



floor, etc., and give rise to pupae, both without traces of wings. 

 Yet fleas and flies differ in that the fleas have similar body somites 

 but the haustellum is lacking, the sucking tube being formed 

 of labrum and mandibles, while the sharp maxillae puncture the 

 skin. Besides Pulexirritans,* the flea that attacks man, many 

 other species occur on other animals. In warm countries the jigger 

 or chigoe, Sarcophsylla penetrans,* attacks man, the female boring 

 into the skin, usually under the nails, and there laying the eggs. 



Order XI. Lepidoptera. 



This group of butterflies and moths is the most sharply limited 

 of any order of Hexapods. The wings, both pairs of which are 

 well developed (rarely lacking, as in many female Psych idae and 

 some Geometridaa), are covered with scales (flattened hairs), and 

 to these are due the frequently brilliant color patterns. Frequently 

 the fore and hind wings are united by hooks (frenulum) on the 

 latter, engaging in a retinacuhim in the fore wing. The mesothorax 

 is large and the smaller pro- and metathorax are closely united to 

 it, giving the region a distinctness from head or abdomen. The 

 mouth parts are peculiar (fig. 489), although foreshadowed in the 

 Phryganids, and not fully developed in the Microlepidoptera. The 

 mandibles are rudimentary or absent, while the fused maxillae, 

 greatly elongate, form the proboscis. Maxillary and labial palpi 

 are present, the former smaller and often degenerate. The de- 

 velopment is holometabolous; the larvae, frequently called cater- 

 pillars (fig. 502), have biting mouth parts, the mandibles very 

 strong; and also silk glands (sericteria), a pair of internal organs 

 which open together on the labium and produce a secretion hard- 

 ening to silk; besides the thoracic legs, prolegs, two to five pairs, 

 are present. The pupae are usually pupae obtectae, and are rarely 

 free. In some the pupae are ornamented with golden spots, whence 

 the name chrysalides often applied to them. 



Sub Order I. MICROLEPIDOPTERA. Small, inconspicuous; at rest 

 holding the wings horizontally over the back ; maxillary palpi very large ; 

 proboscis small. TINEID.E ; the larvae form a tube of the food material 

 which they carry around with them. Tinea pellionella,* the clothes- 

 moth. ToRTRicnxE ; the larvae roll leaves into a tube. Carpocapsa pomo- 

 nella* the codlin moth, the larvae infesting apples. 



Sub Order II. GEOMETRINA. Moths slender, the wings in pattern 

 and shape recalling those of butterflies, but held horizontally when at 

 rest ; ' tongue ' (proboscis) small ; larvae with two, rarely three, prolegs, 

 known as span or measuring worms from their gait. Species numerous. 

 Canker worms (Paleacrita vernata,* Alosophila pometaria,* females 

 wingless), Diastictis ribearia* currant worm. 



