V. DIPLOPODA 433 



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

 Canker worms {Pateacrita vernala,''' Alosophila pomelaria/'- females winglessj. 



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. Hypena humuli* hop worm; Aletia argillacea* cotton worm; Lcncatiia 

 unipunctala* army worm; cut worms. Sub Order IV. BOMBYCINA, silk 

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

 lacking in females; proboscis frecjuently rudimentary; antennje long, pectinate; 

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

 [Bombyx mori'^-), native of China; others, like Tdea polyphemiis* furnish silk of 



■Everyx myroii (from Riley). 



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

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

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

 der, hind wings shorter; proboscis very long; antennae short; larva; naked, with a 

 caudal spine (fig. 459). Phlegcthonihis,'* 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 

 antiapa* 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 rcpugnatoria 

 (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, trachea;, 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 antenna;, but two pairs 



