136 THE CANADIAN ENTOMOLOGIST 



were then rushing in. Though inconspicuous, innumerable May- 

 flies were represented; about half of them, Ephemera simidans 

 Walk, and the other half, three species of Heptagenia; //. pulchella 

 Walsh, //. interpunctata Say, and an undetermined species. These 

 were probably the remains of adults that had finished mating and 

 egg depcsition and had fallen, spent, upon the surface of the lake. 



The insects one finds at the drift-line on any shore fall in three 

 principal categories: 



1. Those present by accident; havang fallen into the lake and 

 been swept up by the waves on to the beach. Here belong repre- 

 sentatives of practically all orders of insects, among which the 

 strong-flying and highly specialized members of the dominant 

 orders do most abound. It is these that have chiefly been noticed 

 hitherto. The lists that have been published by myself, by MivSs 

 Snow (1902) and by Dr. Schwarz show good general agreement. 



2. Those that dwell in the lake, and that, on transformation, 

 leave their exuviae floating on the surface. Here belong mainly 

 three groups of aquatic herbivores: Mayflies, midges and caddis- 

 flies. It is chiefly the cast skins of these, less often the insects 

 themselves, that one finds floating in the flotsam or cast upon the 

 sand. More careful collecting and study of these would doubtless 

 yield data of great value concerning the times and seasons and 

 relative numbers of the insect population of our lakes. 



3. Those that live as scavengers upon the carcases of the 

 drift-line. Here belong especially many beetles of the families 

 Staphylinidai,Histeridae, Scarabaidae and Carabidse together with 

 a number of flies that have flesh-eating larva?. 



Bibliography. 

 1861 Hagen, H.A. Insectenziige. Stett. Ent. Zeit., 22, pp. 173- 



183. • 

 1906 Herms, W. B. An ecological and experimental study of 



Sarcophagidffi with relation to lake-beach debris. Jour. 



Exp. Zool., 4, pp. 45-83. 

 1894 Hancock, J. L. Unusual flights of the grouse-locust. Amer. 



Nat., 28, pp. 483-487, 1 pi. 

 1900 Needham.J.G. Insect drift on the shore of Lake Michigan. 



Occ. Mem. Chicago Entom. Soc, 1, pp. 1-8. 



