10 BULLETIN 720, U. 8. DEPARTMENT OF. AGRICULTURE. 
According to W. Stanley Hanson, of Fort Myers, Fla., mallards 
are effective enemies of another pest of this group, namely, the mole 
ericket. He says: 
My flock of mallards have completely destroyed the mole crickets in my grounds. 
The ducks feed at night, when the little mole, so destructive in certain parts of Florida, 
is doing its work. : 
CRUSTACEANS (0.35 PER CENT). 
Although a considerable variety of crustaceans are eaten by the 
mallard they do not form an important element of the diet. Craw- 
fishes are of most interest among them on account of their destruc- 
tive habits. They were eaten by 51 of the mallards examined, and 
from 4 to 6 specimens were found in some stomachs. Other crus- 
taceans devoured by mallards include water fleas, sand fleas, sowbugs, 
fresh-water shrimps, and crabs. 
MOLLUSKS (5.73 PER CENT). 
Mollusks, the most important element of the animal food of the 
mallard, comprise three-fifths of this and 5.73 per cent of the total. 
Fresh-water snails are represented most numerously, no fewer than 
50 sometimes being taken at a single meal. Small bivalves also are 
eaten and as many as 23 were found in a single stomach. 
OTHER ANIMAL MATTER (0.72 PER CENT). 
Among miscellaneous animal matter taken by the mallard, fishes, 
constituting a little less than half of 1 per cent of the total food, are 
most important. Remains of frogs were found in 19 stomachs. 
One record of especial interest relates to a duck collected in December, 
by J. A. Spurrell, at Wall Lake, Iowa. For two days before this was 
killed it had frequented a small patch of open water in a creek, 
caused by the water from a drain. The bird had eaten two craw- 
fishes and two or more frogs, which it must have secured from the 
muddy bottom to which such animals retreat during the winter. 
Other animals found in mallard stomachs were nematode worms, 
including the so-called hairworms; fresh-water bryozoans, marine 
worms, earthworms, water mites, and spiders. 
Besides the foregoing items of animal food, the following are stated 
by various writers to contribute occasionally to the food of the mal- 
lard: Barnacles, leeches, snakes, mice, salmon eggs, and carrion, 
including dead salmon and other fishes. 
BLACK DUCK. 
(Anas rubripes.) 
The black duck is a close relative of the mallard. In size and 
form the two species are practically identical, and in both the female 
has the same loud resonant quack that distinguishes the mallards 
Pas J AON TOU 
