322 TEXTBOOK OF ZOOLOGY 



are sometimes called. The adults are less than an inch long, with 

 well-developed wings, but with vestigial mouth parts since they prob- 

 ably take no food. The larvae inhabit the bottoms of lakes, ponds, 

 rivers, and creeks, and as a means of protecting their soft bodies 

 they build cases or tubes of small rocks, shells, bits of wood, and 

 plants. The larvae feed upon plant tissue and small animals which 

 they capture in little nets that are placed near the entrance to their 

 case. Pupation takes place in the water. The adults lay their eggs 

 in the water on sticks or stones. About eighteen families are recog- 

 nized. The species Hydropsyche partita Banks and H. scalaris 

 Hagen of the net-making family Hydropsychidae, and Platyphylax 

 designata (Walker) of the family Limnophilidae are common in the 

 western states. 



Fig. 185.— Larva of net-making caddis worm, Hydropsyche. (From Needham and 

 Cliristensen, permission of Utah Agricultural Experiment Station.) 



Order Neuroptera (Nerve Winged Insects). — This order contains 

 the doodlebugs, lacewings, snake flies, dobson flies and mantispids. It 

 is probably the most heterogeneous order of insects; all the species, 

 however, have biting mouths and two pairs of net-veined membranous 

 wings. The larvae are both terrestrial and aquatic, and feed mainly 

 upon other insects. There are thirteen families, but probably the 

 families Raphidiidae, snake flies ; Chrysopidae, lacewing flies ; and the 

 Myrmeleonidae, doodlebugs or ant lions contain insects most gener- 

 ally encountered. 



The lacewing or golden eyes, Chrysopa calif ornica Coquillett, is a 

 beneficial and widespread species. It feeds in the larval stage upon 

 aphids, thrips, scale insects, and psyllids. 



Order Coleoptera (Beetles). — The beetles are world-wide in their 

 distribution and contain the largest number of species of any order 

 in the animal kingdom. They are adapted for an almost unlimited 

 variety of conditions, living on plants and animals, on land, and in 

 the water. They have biting mouth parts, and the first pair of wings, 

 the elytra, are leathery or hard. They feed on all possible kinds of 



