AQUATIC INSECTS IN NEW YORK STATE 291 



f Body densely covered with long, fine setae which are gener- 

 ally barbed and frequently aggregated into a pencil at the 



posterior end of the body Dermestidae- 



ff Body not densely covered with long, fine setae, or, if pres- 

 ent, these are minute and never aggregated in the form of 

 a pencil at the posterior end of the body. No account is 

 talven here of the strong black or brownish chitinized 

 spines 

 g Larvae aquatic 



Ji Antennae as long as, or longer than, the thorax 



Dascyllidae- 

 lih Antennae not as long as the thorax 



i Larvae depressed, with the lateral margins of the seg- 

 ments greatly produced so as to conceal the ventral 

 and lateral portions of the body when viewed from 

 above; with tracheal gills on the abdomen 



P a r n i d a 9- 

 ii Larvae cylindrical; without tracheal gills 



;■ Labrum wanting; each body segment usually with 

 four long, filiform appendages; eight abdominal 

 tergum never with a pair of dorsal spines with 



spiracles at their base Haliplidae 



}} Labrum present; none of the body segments with, 

 long, filiform appendages; eighth abdominal ter- 

 gum with a pair of dorsal spines with spiracles 

 at their base; larvae feeding on the roots of 



aquatic plants Chrysomelidae 



gg Larvae not aquatic 



h The lateral margins of the abdominal tergites dilated so- 

 as to conceal the plurae when viewed from above, the 

 dilatations when elongate, narrowed toward the apex 

 i Body convex, about twice as long as wide; lateral dila- 

 tations blunt and covered with numerous minute 



setae Endomychidae- 



ii Body flattened above, distinctly more than twice as 

 long as wide; the lateral dilatations frequently 

 pointed and never covered with numerous minute 



setae Lampyridae 



hh The lateral margins of the abdominal tergites not dilated' 

 so as to conceal the plurae when viewed from above 

 i Body covered with strong, elongate, black or brownish,, 

 chitinized spines 

 ;■ Median pair of spines of the eighth abdominal ter- 

 gite long and modified into a faeci-fork for carry- 

 ing the cast lai-val skins and faeci, umbrellalike 



over the back Chrysomelidae 



jj Median pair of spines of the eighth abdominal ter- 

 gite not longer than the others, and, if any are 

 elongate, it is the median pair of the ninth ab- 

 dominal tergite 



