Vol. XXvi] ENTOMOLOGICAL NEWS 3 



I. DISTRIBUTION OF THE NYMPHS. 



There are already on record some general observations on 

 the habitat of dragonflies, as in Needham and Hart, '01, and 

 on their distribution in relation to the velocity of water (Need- 

 ham, '02). In this paper some further ecological notes are 

 added and the distribution of 30 species, comprising the 

 odonate population of the small area just described, is re- 

 corded. 



Rapid water forms are few. The damsel-fly, Argia pntrida, 

 is found under the stones in the swift water above the branch- 

 ing of the creek, and the dragonfly, Cordnlcf/astcr dnistati>ps. 

 in the nearby gravel. The latter, covered with sand and with 

 the eyes and caudal respiratory opening arched to the surface, 

 lie quietly waiting for their prey to come within reach of their 

 labia. They are provided with two strong claws on each leg 

 with which they are able to crawl over the bottom. The flat, 

 sprawling Ophiogoinphus lies in the gravel a little farther 

 down stream, where the water flows less rapidly. Everywhere 

 at the edges of the current the damsel fly, Caloptcry.v niacii- 

 lata, climbs awkwardly about the weeds and roots, usuall 

 bearing aloft the three caudal gill plates. In this position they 

 can perhaps see their prey more readily as it moves by or is 

 swept past by the current. Hctacrina amcricana is al-n t.'iind 

 on the weeds in rapid water, the imago appearing in the field 

 August 6th for the first time. 



Quiet water forms are more numerous. Large numbers of 

 Gomphus dcscriptus, G. spicatits. G. rillosipcs and G. soniiifus 

 burrow in the soft mud of the sluggish part of the stream and 

 especially near the head of the pond. A net swept through 

 the debris along the edge of the pond will occasionally catch 

 what seems at first a very dark, almost black leaf, but \vhicli 

 on closer examination proves to be the thinnest, broadesl and 

 most grotesque of all the nymphs, Ffac/cnius hrcristylns. 

 sides these there are little short "masked" T.il.dlulid< 

 lie half buried in the mud or crawl about over the bottom 

 the pond or on the Elodea or other water weeds 

 Libcllnla pulchella, Leucorhinia Intacta, Plathemis 

 Pachydipla.r lon<jipcnnis are all represented in this group. 



