CHAPTER XXVII 



THE NEUROPTERA 



The insects placed in this group, though quite similar in structure, 

 differ markedly in appearance in many cases. They vary much m size, 

 ranging from less than a quarter of an inch to several mches m length, 

 and their wings may be small or large. 



The mouth parts are for chewing or biting, and most of the group 

 feed upon insects and other small animals. The wings are four m num- 

 ber, well supphed with both longitudinal and (with a few exceptions) 

 cross-veins. The larvae in general are active, moving about m search 

 of their prey. A few though, live in the egg sacs of spiders, feeding on 

 the young spiders, and in one or two cases, fresh-water sponges appear 

 to be their food. There is a quiet pupa stage. 

 The group may be characterized as: 



Insects which when adult have two pairs of wings usually large as com- 

 pared with the body and with numerous longitudircal and (in most cases) 

 cross-nei7is. Mouth parts for chewing. Metamorphosis complete. 



So far as is known, none of the Neuroptera are injurious insects and 

 some at least are decidedly beneficial. About half a dozen families are 

 usually recognized and some of these are here considered, either because 

 of their economic importance or because they are large and common 

 enough to frequently attract attention. 



In the family Sialidae belongs the largest member of the order (Fig. 

 217) found in the United States. This is commonly called the Corydahs 

 or Hellgrammite {Corydalis cornuta L.) which is quite common throughout 

 the country except in arid regions. The mandibles of the male are 

 nearly an inch long, slender and somewhat curved; those of the female 

 are short. The distance from tip to tip of the wings when these are 

 extended, may be over five inches, and the size of the insect and the long 

 jaws of the male have led to the mistaken belief that this really harmless 

 animal is dangerous. The egg are laid in large masses on objects which 

 hang over the water, into which the larvae enter on hatching, making 

 their way under stones where they feed for nearly 3 years on the nymphs 

 of May-flies and other insects. Here they are searched for by fishermen 

 to use as bait, and are usually called ''Dobsons." When full-grown the 

 larva makes a cell under some stone close to the stream and pupates 

 for about a month, after which the adult escapes . 



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