274 ENTOMOLOGICAL NEWS. f June, 'l6 



lower the salinity of certain pools to such an extent that one 

 finds larvae of several species of mosquitoes in the same pool, 

 it has been shown conclusively that the resistance of the larvae 

 to high salinities is different, following closely the records of 

 the usual environments of the larvae. 



There is much evidence to indicate that the distribution and 

 time of appearance of the two dominant species of salt marsh 

 mosquitoes is in part dependent on the amounts of salts pres- 

 ent in the marsh waters at different distances from the sea. 

 It is very probable that we shall find that a certain salinity is 

 more favorable to the development of the eggs of one species 

 than another. 



Further discussion of the many experiments performed by 

 the senior author will appear in the Journal of Experimental 

 Zoology and in a technical bulletin of the New Jersey Agri- 

 cultural Experiment Station. 



The Sun- Dance of the Sawfly'* (Hymen.). 

 By PHIL RAU, Saint Louis, Missouri. 



A narrow strip of ground, five feet wide or less, lay between 

 the River des Peres and a high railroad embankment. It was 

 well overgrown at this point with grass and low dock and 

 elderberry sprouts, with some scrubby trees nearby. The 

 sun's rays beat down strongly on this April day, and the breeze 

 was all cut off from this spot, so it seemed a humid, swelter- 

 ing hole. Here in the bright sunshine, hovering above the 

 vegetation, were thousands of sawflies, dancing in swarms 

 like gnats. They were in several distinct groups of a hundred 

 or more. The individuals were in constant motion, flying about 

 with a smooth, gliding stroke in all sorts of round figures, 

 circles, eights, S's, etc., but keeping within the limited space 

 of the group as if that portion of the atmosphere had an invis- 

 ible wall around it. 



Each separate swarm poised in the air in one spot most of 

 the time, but occasionally a whole group would move slowly 

 and imperceptibly, like a rolling, floating cloud, for a distance 



"""Identified by Mr. S. A. Rohwer as Macrophya sp. nov. 



