294 THE CANADIAN ENTOMOLOGIST, 



BEETLE DRIFT ON LAKE MICHIGAN. 



EY JAMES G. NEEDHAM. 



The ill wind that blows insects into a lake may blow the entomolo- 

 gist some good if he be on hand to collect them when they are cast upon 

 the beach. During recent yeais I have gathered much material for class 

 use from the drift line upon the beach at Lake Forest, with great economy 

 of time and labour. After every on-shore breeze following sunshiny 

 summer weather some insects are cast up by the waves, and occasionally 

 there is a great accumulation of them. Twice I have observed accumula- 

 tions of them quite out of the ordmary ; the first time, in August, 1899, 

 when the drift was predominantly crickets of a single species ( Nemobius 

 fasciattts)*, and a second time in June, 1904, when it was predominantly 

 May beetles of a single species ( Lachnostenia fnsca). It is the purpose 

 of this paper to record some observations on this occurrence. 



It was discovered on the afternoon of June nth. The weather had 

 been bright and calm for several days, and the favoring wind was gently 

 blowing from the north-east, and bringing the insects ashore, for the most 

 part alive and in good condition. Two things seemed very remarkable 

 about this drift : first its smell, due to the presence in large numbers of 

 the ground beetle, Calosoma frigidum, incited by their tossing upon shore 

 to emit their pungent, but, when sufficiently diluted, not wholly 

 unpleasant odour ; and second, the preponderance of beetles. It was 

 nearly all beetles, and nearly all the beetles were a single species. The 

 accumulation was hardly sufficient to be called a windrow — rather, an 

 incomplete layer averaging a meter wide, spread out in a long sinuous line 

 at the farthest reach of the waves — ^a ribbon of brown trailed along the 

 lighter coloured sand. There was little cinder flotsam or other trash in it, 

 it was nearly pure insect material — brown, because of the millions of May 

 beetles, hardly one per cent, being anything else. 



I gathered an abundant supply of Lachnosterna and Calosoma, made 

 a few notes and went home. Early the next morning I went again to the 

 shore, a mile farther northward. There, to my great surprise, I found the 

 beach bare. Had I missed my opportunity by putting off till to-morrow 

 a more careful examination ? I walked southward, and soon came upon 

 the smell of it, and then, the drift itself. The wind was still north-east, 

 but insects had ajiparently stopped coming in. Many of the May beetles, 



*An account of this I published in the Occasional Memoirs of the Chicago Entom. 

 Soc, Vol. I., No. I. 



