44 SCHOOL ENTOMOLOGY 



trachea by means of which they breathe. They feed on 

 other small animals in the water. These nymphs have very 

 curiously constructed mouths. The lower lip is prolonged 

 and hollowed out so that the rest of the mouth-parts and 

 the lower part of the head fit into it. Food is captured in 

 this " soup-bowl" and carried to the jaws. (See Fig. 28.) 



Damsel-flies (Zygoptera) , are smaller than the dragon- 

 flies and have the abdomen much more slender. They have 

 the wings suddenly narrowed at about one-fourth of the 

 distance from the base to the tip so that they seem to be 

 stalked. When at rest they hold their wings in a vertical 

 position, slanting backward over the back while the 

 dragon-flies hold theirs spread out horizontally. 



Damsel-fly nymphs are also more slender than the 

 dragon-fly nymphs. They have three long and narrow, 

 oval, leaf-like tracheal gills. 



Nymphs of both the above groups are easy to obtain 

 and make excellent aquarium material. 



36. Neuroptera Proper. Three orders may be in- 

 cluded in this group. All have membranous wings, some 

 with netted veined wings, others with the veins mostly 

 longitudinal. The mouth-parts are typically biting. The 

 development is indirect and the larvae have various forms 

 and food habits, some being aquatic and some terrestrial. 



The order Neuroptera in the strict sense includes the 

 largest and most numerous members of the group. They 

 have finely netted wings usually long and rather narrow. 

 The largest form is the Corydalis or Dobson-fly. This in- 

 sect has a wing expanse of five inches or more. The 

 females have strong jaws but in the males these are 

 greatly prolonged and shaped like a very slender cow- 

 horn. They are not dangerous and their pinch is scarcely 

 painful. Larvae of the Corydalis live under stones in 



