180 
Psyche 
[October 
pected that Lethocerus would likewise have that number. 
This, however, does not necessarily follow, for in the Nepidse 
we have a different number of instars in the different genera, 
Ranatra and Curicta having five, while Nepa has but four. 
Roesel (1755) figured five nymphal stages for the European 
Nepa cinera L. If we can accept as authentic these notes on 
the biology of N. cinera, we have this difference in the number 
of instars occurring within the genus. This is known to be the 
case in the family Veliidse, where in the genus Microvelia we have 
some species with five instars while others have only four. 
Since the fifth instar is of fifteen or more days duration it is 
evident that the growing period, the period of great food con- 
sumption, extends over a considerable period. The progeny of 
one or two pairs of adults could do a great deal of damage in a 
fish pond during their developmental period. The fish culturists 
are surely justified in their denunciation of this form as a menace 
to young fish. 
Literature is replete with references pertaining to the 
ferociousness of this bug. A very remakable account of Letho- 
cerus attacking a fish was recently related to the writer by 
Professor J. R. Parker of the University of Montana. His 
statement follows: ^'some time in September 1923, Mr. C. A. 
Morton of Bozeman with his family was camped on a small 
creek near Ovando, Montana. Early in the morning Mr. Morton 
and another man went out along the creek to get some fish for 
breakfast. In clear, still water they saw a trout about ten or 
twelve inches in length and while watching the trout they 
noticed a giant waterbug lying aimlessly on the surface of the 
water, except for one leg which it appeared to be waving in a 
manner to attract the attenton of the fish. It appeared to be 
successful in this for the trout grabbed the waterbug by the leg 
that had been moving whereupon the bug raised up and sunk 
its beak into the top of the fish’s head. The trout began to 
swim excitedly in circles and jumped clear of the water several 
times. It finally turned over on its back. Mr. Morton waded 
out into the water and caught the fish to which the bug was still 
attached by its beak. He carried the fish back to camp and the 
bug did not release its hold until half way there. Mr. Morton 
