FLAT-WINGED GROUP 



3127 



insect, it extricates itself from its case, and leads an active life, swimming and run- 

 ning with agility. It then climbs up the stem of a plant to undergo its transforma- 

 tion. In some of the smaller species the pupa does not leave the water, but rises to 

 the surface, and the fly emerges from the floating pupal skin. 



Caddice flies are divided into seven families, arranged in two groups chiefly 

 -distinguished by the number of joints in the maxillary palpi of the male insect. In 

 the first section Inaequipalpia the maxillary palpi of the male are composed of 



LIFE HISTORY OF THE CADDICE FLY. 

 i. Larva ; 2. Pupa ; 3. Larva in its case ; 4. Perfect insect. 



two, three, or four joints, never five; thus differing from those of the female, in 

 which the number of joints is always five. This section contains four families 

 the Phryganeidce, Limnophilidce , Sericostomatidce, and Hydroptilidce; the life history 

 of a species of the typical genus (Limnophilus) being depicted in our illustration. The 

 second section ^quipalpa is characterized by the fact that the maxillary palpi 

 of the male are five jointed like those of the female; it includes the families 

 Leptoceridce , Hydropsychidce, and Rhyacophilidce. 



FLAT- WINGED GROUP SUBORDER Planipennia 



The members of this group are distinguished from the last by having both pairs 

 of wings formed nearly alike, and usually provided with a closely reticulated sys- 

 tem of nervures, with numerous transverse branches. The wings which are in- 

 capable of being folded up are for the most part naked; and, when at rest, are 

 turned back in a slanting position against the sides of the body. The mouth organs 

 are well developed, the mandibles in some cases attaining extraordinary proportions. 

 The first family is that of the scorpion flies (Panorpidce) , which have a slender body, 

 and the head turned downward and prolonged in the form of a beak, resulting from 

 the elongation of the clypeus in front, and of the lower lip and maxillaa behind. 

 The mandibles are rather short and narrow; the maxillae, which are fused with the 

 mentum, have five- jointed palpi; and the narrow lower lip is bifid at the extremity, 



