AQUATIC INSECTS IN THE ADIRONDACKS 405 



17 Polycentropus lucidus Hagen 

 8 Hales us no. i (see ^. 567) 



10 H ale s us 



no. 2 (seep. 568) 



16 Hal es us 



no. 3 (j-^^ p. 569) 



17 unclassified 





260 beeti.es 



Donacia emarginata Kirby, of which two were adults, 152 

 were inclosed in puparia attached to the bur reed roots, and a few 

 were free larvae. Since several species occurred about the creek, it is by 

 no means certain that all these belonged to the single species named. 



25 DRAGON FLY NYMPHS 



2 Cordulegaster maculatus Selys 

 4Aeschna constricta Say 



4 G o m p h u s e X i 1 i s Selys 



5 Ophiogomphus aspersus Morse 

 5 Argia violacea Hagen 



5 Sympetrum assimilatum Uhler. Of this species 7 addi- 

 tional specimens were picked from the stems above the water in trans- 

 formation; but one other insect specimen (a stone fly, Leuctra 

 t e n e 1 1 a; was found above the water. 



10 MAY FLY NYMPHS 



1 Ephemera varia Etn. 



4 Ephemerella excrucians Walsh 



5 Baetis pygmaea Hagen 



8 DIPTEROUS LARVAE AND PUPAE 



2 small crane fly larvae (undetermined Tipulidae) 

 4 horsefly larvae (undetermined Tabanidae) 



2 mosquito pupae (undetermined) 



Comparing now the lists made from the two plots we observe some 

 striking differences. Those that appear in the number and variety of 

 aerial forms taken in the first plot, and the paucity of them in the second, 

 may be due mainly to weather conditions: the first plot was worked on a 

 dry, sunshiny morning; the second, on a partly cloudy morning after rain. 

 The .plots agree in that their miscellaneous plant feeders were mainly 

 mollusks and caddis flies. Mollusks seem to constitute a larger bulk 

 than any other single group. Snails were found in the stomachs of frog 

 and fish, and are known to be the food of horsefly larvae (Tabanidae). 

 There are certainly snails enough in the creek to justify the extraordinary 

 abundance of horseflies in this vicinity. 



