135 
April, 1887.] HISTORY SOCIETY OF WISCONSIN. 
Lucanus (lama and Lucanus placidus are rare, but both sexes of 
these stag-beetles, especially the females, were frequently com¬ 
mon. Euphoria fulgida and Orthosoma brunneum were often 
abundant. Chrysomela multiguttis , a beautiful and uncommon 
beetle, appeared in great numbers. Many species of Sphenophours 
and Balaninus , rare elsewhere, were common along the lake 
beach. Many other illustrations of the strange phenomena of 
this accidental distribution might be given, but these will suffice. 
How shall we account for these facts ? There seem to me to 
be three probable causes why we should find so many insects on 
the beach. The first of these is the winds. It is a well-known 
fact that the winds of our lake shore alternate in direction. 
During the day there is a wind from the lake and during the 
night a wind from the shore. Now we have already drawn at¬ 
tention to the fact that most of the beetles of this accidental dis¬ 
tribution were nocturnal, and all of them flying insects. Cer¬ 
tainly it seems very probable that these Coleoptera, while at¬ 
tempting long flights during the night, had been carried out 
into the lake and had fallen into the water to be wafted in by 
the waves when the lake wind set in toward the land. There was 
no means of determining how long these beetles had been in 
the water. The time, of course, varied with the distance they 
fell from land and depended on the tranquil or convulsed con¬ 
dition of the water. 
The second cause seems to be the river and streams. It was 
observed that Coleoptera were especially abundant after rains. 
This was, no doubt, partly due to the greater violence of the 
winds during the rain storms, but the streams and the river also 
were active agents in causing this accidental distribution. The 
foliage surrounding streams and pools is usually the haunt of 
a great number of insects. A sudden rain causes the streams to 
rise and increase in rapidity. These carry away many insects, 
tearing them from the shrubs and grass near and over which 
they flow. Many species, common on the damp earth of the 
hanks, unable to escape from the rising water, are boine along. 
Such are the numerous species of Bembidium and Heterocei as, the 
less common Omophron and Elaphrus . These helpless insects 
