Nov., 1908.] The Broken Hemelytra in certain Halohatinae. 
39 f 
Bergr., Rh. tenuipes Mein, and Trepobates pictus H. S. the 
hemelytra extend much beyond the end of the abdomen, being 
about twice as long as the latter. In all three the male is 
smaller than the female and has a somewhat shorter abdomen. 
In consequence the male has to sit quite far back on the female 
in copulation, in order to approach her genitalia. Now, long 
wings in the female would be decidedly in the w ay of the male, 
as can be readily appreciated, provided they did not actually 
prevent the generative act altogether. In consequence, the 
female finds it imperative to shorten her wings in order to give 
access to the male, which she does by breaking them off at the 
line of weakness, thereby leaving the greater part of the abdomen 
exposed. But while this would seem to be an explanation of the 
act in the female, it scarcely covers the case of the male, since his 
genitalia are in no w ay covered or directly prevented from coming 
into contact with those of the female by his long hemelytra. In 
the length of the tegmina, however, lies the clew. Both Tre¬ 
pobates and Rheumatobates rest very close to the surface of the 
water, so much so that the body of the latter seen from above 
seems to touch the surface, although w^hen seen from the side it 
can at once be noted that such is not the case. Nowq as pointed 
out above, the males in both these genera have to sit far back 
on the females, and in that position the tip end of the hemelytra 
wmuld produce an indentation in the surface film or be slightly 
submerged. The smallness of the bug would tend to make it 
appear that the former would be the case. This resistance, of 
course, would operate in two ways. It would be a great assist¬ 
ance to the unwilling and struggling female in getting rid of the 
amorous yet unwelcome male; and it would be decidedly in his 
way by preventing the approach of his genitalia to hers. Hence 
the male, for similar reasons to the female finds it necessary to 
rid himself of members Avhich, while they may at some period 
subserve a useful purpose, are decided obstacles to the real end 
of insect life. 
The second solution offered in explanation of this self-mutila¬ 
tion is grounded on the following observations. 
The first truncate winged Rheumatobates I captured was in a 
deep currentless pool in a stream, by no means a normal breeding 
place. All the others, as well as the Trepobates were found, as 
previously noted, in a small pond which at a time when St. 
Mary’s Lake had its full quota of both forms in several instars, 
had not a single individual of either on its placid surface. But 
later, when the Lake w^as populous with adults, some fully 
whnged, the pond had on it all these truncate winged individuals 
as well as a few nymphs and some wdngless adults. It may well 
be, therefore, that the object of the wings is to facilitate migra¬ 
tion, either to provide against in-breeding, or to allow their 
