THE LACE-WINGED INSECTS 



(Order Neuroptera.) 



There was a time, and it extended down to comparatively 

 recent years, when all of the insects which would not fit into 

 any of the five principal orders, Hymenoptera, Diptera, Lepidop- 

 tera, Orthoptera, or Hemiptera, were placed in the order Neurop- 

 tera, but entomologists of late years have changed all that, and 

 the old group Neuroptera, as it was formerly considered, has 

 been divided up into a number of distinct orders. 



The first step was to separate those which had a complete 

 metamorphosis from those in which the metamorphosis was 

 incomplete. This resulted in the establishment of only one new 

 order, the so-called Pseudoneuroptera, which included those in 

 which the metamorphosis was incomplete, but the Pseudoneurop- 

 tera has again been split up, and we have the Thysanura, the 

 May-flies, the dragon-flies, the white-ants, the Psocids and book- 

 lice, the bird-lice, the caddis flies and the scorpion flies, all 

 forming distinct orders, which are treated elsewhere in this 

 work. There remain then those of the old order Neuroptera in 

 which the perfect insect has a biting mouth, two pairs of mem- 

 branous wings with many veins, and in which there is a com- 

 plete metamorphosis, the larva being quite dissimilar from the 

 adult, and moreover, in the adults in no case is the head pro- 

 longed into a beak-like structure. Even under this restriction of 

 the old order Neuroptera we have still a number of diverse forms 

 in the order, and these are separated into seven well-marked 

 families. It would not be surprising if the old order were still 

 further split up, and as a matter of fact a distinct ordinal name 

 has been suggested for a group of five of these families. 



The biting mouth-parts of the Neuroptera as limited at 

 present are not used for the purpose of eating vegetation to any 

 extent, since practically all of the insects in this group are car- 

 nivorous and feed upon other insects. Some of them are aquatic, 



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