98 Annals Entomological Society of America [Vol. IV, 



Many times nymphs are collected for rearing in places not 

 often visited. Such nymphs may be transported alive in jars 

 of their native water with plants or stones to furnish forage and 

 foot-hold. Fragile forms like Epeorus and Heptagenia may be 

 better carried in a can of cotton or sphagnum thoroughly sat- 

 urated with water. The nymphs should be carefully placed on 

 the surface with a thin, very wet layer above them. If carried 

 in this way they will arrive at their destination in much more 

 perfect condition than if jostled about in a can of water. If a 

 running water aquarium, or better, a convenient small stream 

 is not available, the nymphs brought home for rearing may be 

 placed in flower-pot saucers in which rapid evaporation will 

 keep the water sweet. Small stones projecting from the water 

 should be provided for emerging places. A cylinder of wire 

 cloth with cheese-cloth top may be slipped over the dish so 

 that the sub-imago may be easily caught. 



In large aquaria where several kinds of insects are kept, 

 care should be taken to exclude carnivorous beetles, and 

 dragon-fly and damsel-fly nymphs for which May-flies are 

 choice food. May-fly nymphs are mostly herbivorous and need 

 only a supply of diatom-covered stones for forage and some 

 aquatic plants like Chara or Nitella upon which they may depend 

 for foot-hold and hiding. Needless to say the temperature of 

 such an aquarium should be kept as nearly as possible to that 

 of the streams. Of the nymphs which I have endeavored to 

 keep in the aquarium of Cornell University, Blasturus cupidus, 

 Callibaetis fluctuans, and Siphlurus alternatus proved most 

 hardy. These lived from one to four weeks in rather adverse 

 conditions, the water in the aquarium having been treated 

 with aluminum sulphate for drinking purposes. 



ECOLOGY AND DESCRIPTIONS. 



The May-flies found during the past summer in or very near 

 the Creek will be grouped under the three family heads given 

 by Prof. Needham in Bull. 86. Notes and description of new 

 species are given under their respective headings. 



Ephemerinae. 



Polymitarcys albus Say. 



Two sub-imagoes were captured near night-fall on June 20. 



