V. DIPLOPODA 



433 



three, prolegs, known as measuring worms from their gait. Species numerous. 

 Canker worms (Paleacrita vernata,* Alosophila pometaria* females wingless). 



Sub Order III. NOCTUINA. Owlet moths; with short bodies; fore wings 

 usually gray and ornamented by two spots and zigzag lines which at rest cover 

 the frequently (as in Catocala*) brightly colored hind wings; 1800 species in 

 U. S. Hvpcna liumitli* hop worm: Aletia argillacea* cotton worm; Leucania 

 unipunctata* army worm; cut worms. Sub Order IV. BOMBYCIXA, silk 

 worms. Body large, woolly, usually broad dull-colored wings; occasionally 

 lacking in females; proboscis frequently rudimentary; antennae long, pectinate; 

 larvae with well-developed spinning powers. Most important is the silk worm 

 (Bombyx won'*), native of China; others, like Tdea polyphemus,* furnish silk of 



FlG. 489. Everyx myrun (from Riley). 



value. Many damage forest trees, among them the tent caterpillars (Clisio- 

 campa*) and the imported gipsy moth Ocneria dispar (fig. 72). Sub Order V. 

 SPHINGINA. Hawk moths (fig. 489), body long, stout; fore wings long, slen- 

 der, hind wings shorter; proboscis very long; antenna? short; larvae naked, with a 

 caudal spine (fig. 459). Phlegeihontius* tomato and tobacco worms. SESIID^E, 

 'clear wings,' resemble bees and wasps. 



Sub Order VI. RHOPALOCERA, butterflies. Body slender; wings held 

 vertically when at rest, proboscis long; antennae clubbed at the tip; larva' usually 

 spiny; puoae hung by a thread, never a cocoon. Species numerous. Vanessa 

 anthpa*- lives over winter; Pieris* attack cabbages, etc.; Papilio* swallow tails. 



Class V. Diplopoda (Chilognatha). 



The Diplopoda are usually united with the Chilopoda in a group of 

 Myriapoda; but while they agree in having a head followed by numerous 

 foot-bearing segments, they differ so greatly that no union is possible. 

 The body is nearly cylindrical, although in Polydesmids lateral outgrowths 

 give it a flattened appearance; the legs are close together on the ventral 

 surface, with the tracheal openings near them, while on the sides of the 

 body are other openings of defensive glands, the foramina repugnatoria 

 (fig. 490). Each segment of the body except the first four or five bears 

 two pairs of appendages, which, with a similar duplicity in chambers of 

 the heart, tracheae, ganglia, etc., shows that a fusion has occurred. The 

 anterior somites bear at most but a single pair of legs; both legs and 

 antennae are short. The head bears, besides the antennae, but two pairs 



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