SCIENTIFIC SURVEY. £07 



the abdomen with two terminal long filiform appendages. The 

 females of Perla are shorter and have much smaller wings than the 

 males. The pupae are active, with prominent wing-pads, they are 

 found in rivers under stones, while the imagines fly on the bank, 

 or are found resting on leaves, alwaj's in damp low situations. 

 Pteronarcys is distinguished from other genera by its large size, 

 and possession of several pairs of outer tufts of filaments serving 

 as organs for respiration. 



Myrmeleon, the Ant-lion is the type of another family, very car- 

 nivorous in their habits. They resemble the Libellulidae very much 

 except in having long antennae. The larvae, on the contrary, bear 

 a close resemblance to that of Chrysopa figured below. It makes 

 a pitfall in sand in which it hides, only showing its large jaws open 

 to seize anj' insect that may fall into them. These insects have 

 not been found in Maine. 



Hemerohiidae. Aphis-lions, Lace-winged flies. Chrxjsopa, here 

 figured, has a slender body, delicate, Fig. 29. 



gauze-like wings, and is generally green, 

 with golden eyes. When disturbed it ^ ^>7 

 throws out a fetid smell. They are very 

 abundant in summer wherever plant lice 

 are found, laying their eggs placed on 

 long pedicils on leaves. The larvae (Fig. 30) feed ravenously on 

 the lice, and when other food is wanting, on each fig. 30. 

 other. They turn to pupae late in summer and pass \/v 



the winter in that state. Gardeners in Europe \;W^ 

 search for these Aphis-lions and put a pair or two ^^^^ 

 on trees overrun with lice which they soon depop- -^'^-^^^ 

 ulate. Hemerobius proper, has broad pale rings, 

 and is of smaller size than Chrysopa. 



Sialidae. This group comprises aquatic, sluggish '^^ 



insects of moderate or of immense size. They have large heads 

 with large jaws, square thoracic rings; and the abdomen in 

 Corydalis cornuta has long anal filaments. This genus expands 

 five or six inches, and the head is armed with immense horns, be- 

 sides the long antennae, while the long wings are folded horizon- 

 tally. In Sialis americana, an insect not an inch long and found 

 resting on leaves of trees in their perfect state, the wings are de- 

 flexed on the sides, as in Chrysopa. 



Panorpa represents another family, which have the head long and 

 narrow, wings narrow and banded, and the tail armed with a for- 



