NEUROPTERA. 163 



position, throwing the body into the shape of an S, or they roll up spirally like 

 a saw-fly lai-va, and fall into the cracks in the ground. In this position they are 

 like a ball bristling with spines, and are on all sides inaccessible to the attacks of 

 smaller enemies, while reminding one of a hedgehog or porcupine among the higher 

 animals. 



On approaching the time of entering the chrysalis state they bury themselves in the 

 earth one or two inches, and, hollowing it out by the spiral motions of the body, form 

 an oval hole. In this little cell the larva changes, its body becoming shoj-ter, thicker, 

 paler, indeed almost white, while the spine-like appendages become flabby, and lie on 

 the side of the body instead of standing erect ; meanwhile the larva, like most cater- 

 pillars, keeps turning on its longitudinal axis. After a period of ten days it casts 

 the larva skin and appears as a slender white pupa, and fourteen days later the imago 

 appears. 



A still more remarkable insect is the Snow Insect or Boreus. It is a smaller insect 

 than the foregoing. In the males the wings are very rudimentary, being about half as 

 long as the abdomen, and narrow and stiff 

 like a style, being entirely useless for flight. 

 The female is' entirely wingless, and is pro- 

 vided with a large sabre-like ovipositor. 

 The skin is dark, with bronze tints, and 

 altogether it is a remarkable insect. More- 

 over its habits are singular. It occurs in„„„„ ^„ ■ ^ , ^ 



° . Fia. 236. — Pupa of Boreus, snow insect, enlarged. 



moss, and though a rare insect in general 



is found in considerable abundance when it does occur, leaping about on the snow. We 

 have in the northern States two species, both described from New York by Dr. Fitch. 

 Boreus nivoriundus is about one-seventh of an inch long, and is reddish, with a bronze 

 tinge, while B. brunialis is entirely brassy black, and is smaller than the other species. 

 Boreus californicus was found near Fort Bidwell in northern California about the 

 middle of December, when they were observed walking on the snow in the morning, 

 disappearing when the sun shone brightly at noon. 



In the Phetganeid^ or caddis flies the body is slender, the thorax rounded. 

 There are no jaws in the adults, which closely resemble some of the moths. The 

 larvae are aquatic, and live in cases or tubes formed from the surrounding materials. 

 The members of this family are quite unlike any other Neuroptera, and form a sub- 

 order (Trichoptera) by themselves, though the Panorpidce approach them in some 

 important respects, and serve as connecting links between the present and the other 

 families of Neuroptera. The larvae of the Phryganeidae are called Case Worms or 

 Caddis Worms, and the imagines are called Caddis Flies. 



The bodies of the caddis flies are cylindrical and have much the same shape as that 

 of a moth, the head being small and rounded, the thorax spherical (owing chiefly to 

 the small collar-like prothorax). Moreover the jaws are either rudimentary or wanting, 

 not being used in adult life, while the wings ai-e shaped like those of a small moth, 

 i being folded roof-like on their back, and the venation or !^eins of the wings resemble 

 those of the Lepidoptera, the short transverse veins being few in number. A number 

 of species of the smaller caddis flies would be easily mistaken for moths, and owing to 

 the close resemblance in nearly all the parts of the body to the Lepidoptera it has been 

 suggested that Lepidoptera have either descended from the caddis flies or that the two 

 groups have had a common origin. 



