THE PHRYGANJN^E. 355 



They have long setaceous antennae ; their wings are of 

 an unequal size, and are laid in repose, like those of a 

 moth, over their back ; their legs are usually long, and 

 their tibiae are variously furnished with spurs half way 

 up its shank. In their larva state, they reside in 

 cylindrical cases, but which, in Hydroptila, are kidney- 

 shaped, which are composed of a variety of substances, 

 as bits of stick or straw, or of small shells, or sometimes 

 of small stones, which are attached together by a silky 

 substance spun by the larva. The majority are con- 

 veyed about, either by the motion they can themselves 

 give to their case, or by the current of the water ; and 

 other cases are permanently affixed to stones beneath 

 the water ; and it is probable that^ upon each change of 

 skin, a fresh case is made. Like most aquatic larvae., 

 they breathe by branchiae. Unlike the majority of the 

 rest of the Neuroptera, these larvae are very dissimilar 

 to the perfect insect, and which, extracted from its 

 case, is a soft worm-like creature, with the anterior 

 segments somewhat horny. Their branchiae are placed 

 along each side of the abdomen ; they are setiform, and 

 are usually arranged in stars, radiating from a centre. 

 Their anal segment has appendages which, as their 

 cases are open at each extremity, admit of their being^ 

 used as feet, but which vary in structure in the genera. 

 They are indifferent in their diet, feeding as willingly 

 upon aquatic plants as upon other insects, and they are 

 excessively voracious. They are but one year under- 

 going their transformations, and to effect this, they 

 close both the apertures of their cases. They undergo 

 a complete metamorphosis ; and the perfect insect then 

 flies forth to feed upon the juices of flowers ; and when 

 impregnation has taken place, the female deposits upon 

 some water plant a mass of eggs enveloped in a thick 

 jelly-like substance. The most remarkable genera are 

 Acentropus and Hydroptila, in which, possibly, the 

 resemblance to the Lepidoptera is the strongest. In 

 Mystacides, the antennae are excessively long; in 

 Barypenthus, and in Sericostoma. the middle spurs of 

 A A 2 



