1911] May-Flies of Fall Creek, N. Y. 109 



Leptophlebia praepedita Etn. 



This species has already been noted by Prof. Needham (Bull. 

 86, N. Y., State Mus.) This species is diurnal. Companies 

 of them were seen dancing in bright sunlight on the afternoon 

 of May 29, June 3, 20 and 21. A mating flight on May 29 

 occurred about five o'clock just above a dashing water-fall of 

 Fall Creek. As the swarm rose and fell at alternate heights of 

 ten to fifteen feet their silvery wings and bodies shone in the 

 sunshine like falling snow-flakes. After half an hour of con- 

 tinuous flying and soaring the swarm gradually disappeared. 

 Of the specimens captured all were males. Earlier in the after- 

 noon a similar but smaller swarm was seen flying above a small 

 tributary rill. This swarm did not at any time fly higher than 

 six feet above the water. Practically the whole swarm was 

 captured at one sweep of a large net. Of the captured insects 

 forty were males and one was a female. 



Choroterpes basalis Banks. 



This species is plentifully represented in the Creek. The 

 nymph is described in Bull. 86 of the N. Y. State Museum. 

 Little attention was given to this species beyond the collection 

 of nymphs which were constantly associated with Heptagenia. 



Ephemerella. 



This genus is nearly as diversified in habit as Leptophlebia. 

 The nymphs have been found in pipe drains, in the gravel and 

 trash of still pools, beneath leaves in springs, in the border 

 waters of the creek and in its swiftest ripples. Like Lepto- 

 phlebia they have been found in rather small numbers and 

 widely scattered. My dates for rearings and captures range 

 from the second week in May to the last of July. Better 

 results would have been obtained if attention had been paid to 

 this group earlier in the season for some species were very rarely 

 found by May 10th. 



Ephemerella serrata sp. nov. 

 Occurrence, habitat. The small nymph of this species was 

 found occasionally in restricted areas of the upper Creek where 

 it crawled about on stones, or in the trash, which was washed 

 by running water. It was found in similar situations at Shef- 

 field, Mass. My reared specimens of this species are dated 



