578 NEUROPTERA. 



NEUROPTERA. 



These insects have the body, as a whole, more elongated 

 than in other insects, with large broad, net-veined, thin, mem- 

 branous wings, both pairs being very equal in size, the anterior 

 pair being sometimes smaller than the hind wings, while in 

 some genera the hind ones are either diminished in size or 

 obsolete. The mouth-parts are free, the mandibles being well 

 developed, and the abdomen is long and slender, with the 

 genital armor always present, but made on the simplest plan, 

 not forming a sting. The metamorphosis is either incomplete 

 or complete ; accordingly the pupa is either active or inactive 

 and Avhen inactive resides in a cocoon. The greater number 

 of species are aquatic ; and several degraded forms (Lepismu, 

 etc.) bear a strong resemblance to the Myriapods. 



The description of the head and mouth-parts of the Orthop- 

 tera applies well to the Neuroptera, but the head is horizontal, 

 flatter, and the mouth-parts are less symmetrical, certain parts 

 being greatly developed over others. As a general rule that 

 part of the head situated behind the mouth is larger, in propor- 

 tion to the rest of the head, than usual in the larvae of the 

 higher insects, and also the mouth-parts are much larger and 

 less compact. Thus the head of a Nem-opterous larva may be 

 actually larger than the entire thorax of the same insect ; in 

 the Hymenopterous and Lepidopterous larvae it is the reverse, 

 the head is often smaller than even the prothoracic ring. 



The mouth-parts are inclined to become very large, and in 

 the larva of Libellula the labium is enormously developed, 

 masking the jaws and other parts when at rest, and capable 

 of great extension, while it is armed with powerful hooks, 

 being modified palpi, for seizing other insects. 



The thorax is large, the segments being well developed, and 

 the prothorax is usually large and square, but in what in man}- 

 respects are the most typical insects of the group, the Ephe- 

 meridce and Libellulidce, the prothorax is very small, as in 

 the highest insects, and in the latter group the greatly enlarged 

 flanks of the mesothorax seem to take its i?lace. 



