221 



margin of stigmatal field ; ventral blood-gills present or absent. Body 

 with short silky pubescence or bare ; bristles absent. 



Pupa. — Head without chitinized protuberances; palpi straight. 

 Thoracic respiratory organs long and slender, sometimes pointed 

 apically. Legs extending much beyond apices of wings. Abdomen 

 with weak armature, consisting of 1-3 transverse bands of weak 

 spines and some longer slender hairs, or of only weak hairs, the seg- 

 ments with the usual transverse incisions, giving them a divided ap- 

 pearance. 



HABITS OF LARVAE 



The larvae of the genus Via are fungivorous, living usually in 

 Polypori ; those of Limnophila and Bpiphragma are aquatic or semi- 

 aquatic, feeding upon algae and decaying vegetable matter, the last- 

 named genus occuring in dead stems of plants. 



HABITS OF IMAGINES 



Most species of the subfamily fly in the evening, and they are not 

 uncommonly attracted to lights. 



Keys to Genera 

 larvae 



1. Apical segment with 2 long and 2 short processes which are fringed 



with very long hairs; labium divided centrally Limnophila. 



— Apical segment with 4 or 5 short, pointed processes which are in- 



conspicuously or not at all fringed 2 



2. Apical segment with 4 processes Epipliragma. 



— Apical segment with 5 processes Via. 



pupae 



1. Thoracic respiratory organs rather short, swollen at base and acute 



at apices Epipliragma. 



— Thoracic respiratory organs long and slender, of nearly uniform 



thickness throughout their entire length, not acute at apices .... 2 



2. A number of hairs on frons between antennae Limnopliila. 



— No hairs on frons between antennae Via. 



Limnophila Macquart 



GENERIC CHARACTERS 



Larva. — Head moderately chitinized, the ventral, median posterior 

 opening large. Antennae short and slender, with a long apical hair, 



