WATER MARGIN 



219 



The day was warm and a strong southeast wind was blowing. In mid- 

 afternoon there was a small shower and the wind changed to a strong 

 northeaster. At 4 p.m. we paid another visit to the beach. The waves 

 were rolling moderately high and the beach was covered with a host of 

 insects, chiefly alive, though many were dead. The beach was lined 

 with live forms crawling away from the water. Often the live ones 

 were still clinging to small sticks upon which they had floated ashore 

 by the fifties. These insects represented all orders, belonging to various 

 habitats near the lake. There were large forest margin bugs, potato- 

 beetles, lady-beetles, horseflies, robber-flies, butterflies, water, marsh, 

 prairie, and forest inhabitants which had been blown in the lake in the 

 forenoon. With them were occasional fish, some with large round scars 

 showing the work of the lampreys (166); others that had evidently died 

 from other causes. On other occasions dead muskrats, dogs, cats, birds 

 of all kinds have been found in these lines of drift (167). On one 

 occasion, birds, chiefly downy woodpeckers, were so numerous that 

 one could almost step from one to the other, had they been equally 

 spaced over the half-mile of beach upon which they were strewn. Need- 

 ham (168) has studied the drift and gives an account of the numerous 

 beetles that came ashore. 



In a few days after such a storm, one finds the various insects that 

 washed ashore either lying dead, or alive under the chips, sticks, and 

 carcasses which came with them. Flesh-flies detect the presence of the 

 food very quickly, and often come to dead fish inside of ten or fifteen 

 minutes (169). These flies belong to the families Sarcophagidae and 

 Muscidae. As a result of storms which float the bodies of animals 

 ashore from time to time, the flies always find a sufficient quantity of 

 decaying flesh to maintain the species. The flies are in competition with 

 a large number of scavenger beetles: e.g., a hister (Saprinus patruelis 

 Lee.) which feeds on carrion (Stereopalpus badiipennis Lee). Several 

 species of rove-beetle complete a partial list of the other scavengers 

 usually more or less abundant on the shore. The larvae of Dermestidae 

 have been found under the dry remains of fish which had been worked 

 over by the carrion-feeders. 



Preying upon these and upon the insects that come ashore are the 

 tiger-beetles (Cicindela hirticollis and cuprascens) (151, 170) which pick 

 up the flies that they often are able to seize while alighting on the ground. 

 They also capture the maggots of the flies when they leave the carrion, 

 and the lady-beetles and other small insects which come ashore. Several 

 species of the ground beetles and occasional shore bugs (Saldidae) are 



