AQUATIC INSECTS IN THE ADIRONDACKS 55 1 



KEY TO GENERA OF HEMEROBIIDAEi 



a Branches of the radical sector arising (i. e. separating from vein Ki ) hy a 

 common stalk (fig. 32) 

 h Humeral cross vein recurrent, and hearing several hranches on its outer 



side Polystoechotes 



bb Humeral cross vein unbrauched and not recurrent 



c The median vein repeatedly forked ; some of the hranches of vein Cui 



forked . Si syra 



cc The median vein hut once forked ; the branches on vein Cui simple 



C 1 i maci a 

 aa Branches of the radial sector arising separately from vein Ri 

 d Humeral cross vein recurrent and bearing several branches on its outer 



side Hemerohius 



dd Humeral cross vein unbranched and not recurrent Micromus 



The typical genus, Hemerobius, includes the majority of the 

 described species of the family. Its larvae are commonly arboreal, and 

 feed on aphids, small moth larvae, etc. They commonly spin their loose 

 cocoons of silk in crevices of the bark and there undergo their transfor- 

 mations. 



Of the American genus Polystoechotes, which contains our 

 largest species, the life history has not been recorded. Hagen, char- 

 acterizing the genus in 1861 [Synopsis Neuroptera of North America)^ 

 wrote " Larvae perhaps aquatic "; and this opinion has been handed down 

 to the present time. I obtained some of the eggs in July by confining some 

 of the females of Polystoechotes in a pasteboard box. The eggs 

 were dropped at random on the bottom of the box, where they rolled 

 loosely about. They were chalky white in color, oblong oval in outline, 

 with surface minutely granular. Some were dropped on water in a glass, 

 where they floated high and dry; and the next day were overgrown 

 with molds. The others were left in the box, and the box closed that 

 more eggs might be obtained : instead, the females ate the eggs already 

 laid, and then began to devour one another. Thus I lost an excellent 

 opportunity for studying the earlier part of the life history of this interest- 

 ing insect. The character of the eggs, and the haunts of the females 

 lead me to suppose rather that the larva is terrestrial or arboreal, as in 

 Hemerobius. 



Polystoechotes punctatus (pi. 26, fig. 2) Fabr. was not un- 

 common during the month of July. It was taken a few times in our trap 

 lanterns ; but, for some> to me unknown reason, was found in numbers only 

 in the Saranac Inn railway station. At the windows of the depot one might 

 expect to gather with little effort a dozen or more specimens in an evening. 



1 Three North American genera remain as yet unreported from New York state: Dilar, with a 

 single species, distinguished from the remainder of the family by the possession of ocelli; 

 Psectra, with a single species, distinguished by its having normally but two wings; and 

 Berotha, with tliree species, distinguished by having the apex of the wing very acute, and a 

 notch or excision in the outer wing margin. 



