96 Annals Entomological Society of America [Vol. IV, 



Fall Creek cuts downward through a narrow gorge, widens into 

 the artificial pond known as Beebe Lake, hurries through a 

 deep gorge and over a series of falls, cascades and riffles to the 

 marsh below. This lower creek is inhabited by those true 

 dwellers of the rapids, Chirotonetes albomanicatus and Baetis 

 pygmea. 



To the north of the lower portion of Fall Creek a small 

 streamlet known as Pleasant Brook follows a parallel course to 

 the lowlands. Its pools and cascades shelter a fauna similar 

 to that of Fall Creek if somewhat less rich. This brook 

 possesses the advantage of small size which makes its study easy. 

 Devoid of tributaries to flood it in time of rain, and shut in by 

 shrubbery, this stream furnished a safe place for the rearing 

 cages of nymphs which were captured in Fall Creek. 



METHODS OF REARING AND COLLECTING. 



Rearing and collecting were begun on April 1, and continued 

 to August, 1, after which only irregular collecting trips were 

 made to the Creek. The only satisfactory method of rearing 

 May-flies is one which keeps them in their own environment 

 or in conditions closely imitating it. For this purpose Prof. 

 Needham used a cylindrical cage made of wire cloth with a 

 cheese-cloth cover. Such cages are the most convenient for 

 carrying in a knapsack and many May-flies have been success- 

 fully reared in them. The space within them, however, is 

 small and all surfaces are perpendicular to the water. If the 

 imago becomes entangled, or if it is not strong enough to keep 

 its footing on the upright surface it falls back into the water 

 and drowns, or at least will never be able to transform. When 

 two or three insects are in the same cage, particularly if the cage 

 is in a strong light, there is danger of one or all falling into the 

 water. For these reasons I have designed another cage, which 

 though less conveniently carried about, has the merit of being 

 more roomy and of supplying one slanting surface. This cage 

 may be made of fine copper or galvanized wire cloth. A stiff 

 cloth which will not bend easily will make the best cage. The 

 cages which I used in Fall Creek were about five inches square 

 on the bottom and five inches in height. Such a cage is easily 

 cut and folded from a single piece of wire cloth. In the dia- 

 gram shown in Fig. 2, the continuous heavy lines represent the 

 cut edges, the lighter lines the folded edges of the laps, and the 



