OF WASHINGTON. 211 
water. A difficulty is experienced with those species which are about 
equally divided in regard to living and drowned specimens. Here it ap- 
pears probable that the living specimens have been in the water for a 
short time and the dead specimens for a longer or very long period. Such 
species naturally occupy an uncertain, or at least intermediate, place on 
my list. 
That all terrestrial or semi-terrestrial, and, I may add, also most of the 
truly aquatic insects in the imago state get finally drowned in water, ad- 
mits of no doubt, but how long they are able to sustain immersion can 
only be ascertained by experiment with each species. It is evident, how- 
ever, that this time varies according to the adaptability of the species and 
to a multitude of circumstances, such as temperature and condition of the 
water. If insects happen to cling to pieces of wood or other floating ob- 
jects they will be able to sustain the exposure much longer than those 
which simply float on the surface of the water. Insects with exposed 
stigmata are evidently less fit for long immersion than those with pro- 
tected stigmata, and those with a nervous temperament and which exhaust 
themselves by violent movements succumb, no doubt, sooner than those 
with a more phlegmatic temperament. Among the Lake Superior insects 
washed ashore we notice many strictly nocturnal species, and if these are 
washed ashore, say, at noon of a certain day, it is evident that they must 
have been in the water at least since the previous night, and probably since 
the earlier hours of that night, since most nocturnal insects fly soon after 
dark and not often after midnight. But we have no means of ascertaining 
whether such insects have been in the water for one day or two, or even 
longer. With the diurnal insects this uncertainty is still greater. The 
washed-up specimens may have been only a few minutes in the water, or 
for some hours, or for one or two days, or still longer. That there is a 
great diversity in this respect is evident from the immense multitude of 
specimens found on a single point. The}' cannot have possibly dropped 
in the water at a single spot and at the same time. Some, no doubt, 
dropped into the lake a short distance from the shore; some farther out, 
and still others very far perhaps many miles from the shore. In the 
summer of 1874, Mr. H. G. Hubbard and myself passed on a raft of logs 
through Lake Sinclair. This raft was more than a hundred feet wide 
in front, and it acted like a great collecting machine, fishing up every- 
thing that came in its way. The raft was covered with specimens of all 
Orders, and this happened at a distance of at least five miles from the near- 
est land. How long it would take these insects to be driven ashore by a 
favorable breeze is not possible to tell without special observation ; but 
from what we saw at Lake Superior this process is accomplished more rap- 
idly than one is inclined to suppose. 
With all these drawbacks and uncertainties I present herewith, for what 
it is worth, the following table of Orders, condensed from my notes and 
arranged according to their smaller or greater ability to withstand immer- 
sion in the icy water of Lake Superior. If this table should be arranged 
