THE CANADIAN ENTOMOLOGIST. 237 



single larva among them. On the sloping or rocky part of the beach the 

 puparia rest upon dry ground and become themselves almost entirely 

 dry. Here they remain for several days exposed to the warm sun, and 

 it is certainly remarkable that under these circumstances they retain their 

 vitality. ** From a tin box full of the puparia which I picked up on a 

 dry spot on June X4th, the flies began to hatch by the thousands on Tune 

 19th. In the middle of June, the weather being rather cool, the imagos 

 were not very abundant at the lake. They rest on the wet sand or on the 

 rocks, and here, in the little pools between the rocks, we observed that 

 the flies deliberately go under the water to a depth of two or three inches. 

 Whether they do this for the purpose of ovipositing or of feeding on the 

 algae has not been ascertained. On June 25th the number of flies had 

 already considerably increased, but on July 4th, when the little bathing 

 establishment at Syracuse, on the eastern shore of the lake was visited, the 

 number of flies was really alarming. On this point there are numerous 

 shallow pools close to the lake beach, between the railroad dam and the 

 dykes of the salt works, and the flies completely covered the edges and 

 the surface of the pools, forming an unbroken coal-black mass. No 

 observations on other insects would have been possible under these cir- 

 cumstances ; but, fortunately, the flies could be driven away to some 

 extent, and the roar of the rising flies is such as to drown the noise of the 

 railroad trains passing close by. 



The question where the larvae of this Ephydra breed has not been 

 fully settled by us. Numerous larvae were found in the pools between 

 the large stones near the famous Black Rock. They were still more 

 abundant in the little sulphurous streams on the salt flats, thickly cling- 

 ing to the slimy, thread-like algae, upon which they probably feed. But 

 all larvae from these two sources account only for a small fraction of the 

 prodigious number of puparia along the lake. It is evident that the 

 majority of the larvae must live in the open lake, where numerous reefs 

 in shallow water appear to be favourable breeding places. 



Whether the numerous Crustacea (genus Artemia) that live in the lake 

 feed on the Ephydra larvae, or whether the sea-gulls and other birds so 

 abundant on the salt flats feed on the puparia has not been ascertained ; 

 nor did we see any trace of the Chalcid parasite reported to infest the 



**During calm weather the puparia must float for several days on the lake, and it 

 would seem probable that the imagos are able to issue from the pupa on the surface of 

 the water. 



