OF WASHINGTON. 209 
tion, but upon observation in the field, and require some preliminary ex- 
planation regarding the circumstances under which the observations were 
made. 
The occasional accumulation of large masses of insects of all Orders 
washed ashore on the, sandy beaches of our great lakes or along the 
ocean has often been mentioned in print and otherwise; but since, so far 
as I am aware, nothing definite has ever been published concerning this 
phenomenon I take this opportunity to place on record the results of ob- 
servations carried on through several years along the Upper Lakes, and 
more especially Lake Superior. To the latter locality I refer more 
especially because here my friends and myself have been at several points 
all around the lake in different years, and also because the insect fauna 
of the Lake Superior region is infinitely richer than that of the Lower 
Lakes. Moreover, in the boreal climate of Lake Superior the appearance of 
the entire insect fauna is a nearly simultaneous one, whereas on the Lower 
Lakes the various species appear successively from early spring through- 
out the whole summer. At Lake Superior the time of appearance and 
swarming of most insects is compressed into the short time from the be- 
ginning of June till the middle of July. During these few weeks untold 
millions of insects fall into the lake, but whether attracted by the glitter- 
ing surface of the water or from exhaustion, having flown too far out into 
the lake, cannot be ascertained. Under certain conditions these speci- 
mens are washed upon the beach, reaching the same either alive or 
drowned, and form, on a favorable day, intermixed with the various debris, 
a windrow sometimes several inches in height and width, and continuing 
for miles along the shore until the direction of the beach changes. 
This accumulation of specimens, observed by many entomologists, is 
usually said to occur during or after a storm ; but this is quite incorrect, 
at least so far as the Lake Superior region is concerned. If the lake is 
angry, the waves break long before reaching the shore, the sand is stirred 
up by them, and all insects that are washed ashore are at once buried in 
the sand, whence they are unable to extricate themselves, and where 
they cannot be seen. Only the strongest among them e. g., the genus 
Sphenophorus of the Coleoptera survive the general slaughter. To pro- 
duce a large accumulation of specimens on the beach, a gentle but steady 
breeze must prevail, for at least several hours, directly toward the shore, 
and must be preceded by warm weather. If the breeze is offshore, or even 
obliquely toward the shore, or changeable, or if the weather has been cold 
a day or two before, no accumulation of specimens takes place.* Such 
favorable combination of meteorological conditions does not often occur 
at a given place of the lake shore, and one can spend a whole season at the 
*Th. v. Siebold (Beitraege zur Fauna Preussens, 1849, P- 6) refers to 
this phenomenon as observed by him at the Baltic Sea, near Danzig, 
Prussia, after the first days of spring, and states that the insects are washed 
ashore by a light breeze blowing inshore. 
