FOOD HABITS OF SHOAL-WATER DUCKS. 47 
ing water bugs (Naucoridae), of which the small, flat, predacious 
bugs of the genus Pelocoris had been taken by 43 of the ducks; the 
giant water bugs (Belostomatidae), represented by the genus Belostoma 
in 37 stomachs; water striders (Gerridae), found in 30; back-swimmers 
(Notonectidae), in 20; and water boatmen (Corixidae), in 15. Bugs 
-of the last three families mentioned are without exception very 
active in their movements on or in the water, and their presence 
in so many stomachs of the wood duck no doubt is accounted for 
by their great abundance in lakes and rivers throughout most of 
North America. One wood duck taken at Alden, Wis., in August, 
1908, had been feeding upon a species of plant louse (Rhopalosiphum 
nymphaeae) which in certain states of its development inhabits the 
leaves ot waterlilies. The bird’s gizzard contained about 1,600 of 
these plant lice, as well as other insects and seeds. 
BEETLES (COLEOPTERA), 1.02 PER CENT. 
Beetles of at least 15 families were represented in the food of the 
wood ducks examined. Of these the water scavenger beetles (Hydro- 
philidae), predacious diving beetles (Dytiscidae), and leaf beetles 
(Chrysomelidae) were most commonly taken. The first two families 
mentioned, as their names imply, are strictly aquatic, while the third 
was represented almost entirely by beetles of the genus Donacia, many 
of which feed upon aquatic plants, such as the pondlily, spatterdock, 
etc. Twenty-three of these beetles (Donacia cincticornis) were found 
in one stomach, together with a large number of seeds of the tuberous 
white waterlily (Castalia tuberosa), the plant on which they probably 
were captured. Two other strictly aquatic families, the whirligig 
beetles (Gyrinidae) and crawling water beetles (Haliplidae) were well 
represented. Six genera of ground beetles (Carabidae) were identi- 
fied, and the leaf chafers (Scarabaeidae), long-horned beetles (Ceram- 
bycidae), and snout beetles (Curculionidae) had been eaten in con- 
siderable numbers. The fact that scarabaeid beetles have been eaten 
is often detected by the presence of small, hard grinding plates from 
their jaws, which frequently persist in bird stomachs long after all 
other parts of the beetles have been digested. Peculiar little silken 
cases containing eggs of water scavenger beetles, usually attached to 
a submerged leaf or to the body of the female beetle herself, are not 
infrequently found in duck stomachs. In two from Louisiana they 
made up 70 and 77 per cent, respectively, of the total contents. 
GRASSHOPPERS, CRICKETS, ETC. (ORTHOPTERA), 0.23 PER CENT. 
_ Grasshoppers of the genus Orchelimum were found in the stomachs 
of 11 wood ducks from Missouri; 39 mandibles, representing at least 
20 grasshoppers, were present in one stomach; 8 wood ducks had 
eaten grouse locusts (Tettiginae). 
