20 BULLETIN 862, U. S. DEPARTMENT OF AGRICULTURE. 
duck had eaten 1,630 seeds of knotgrass (Polygonum aviculare). 
Seeds of dock (Rumez spp.), another plant of the smartweed family, 
had been taken by 5 birds. : 
ALGAE, 4.63, PER CENT. 
Musk grass (Chara sp.) forms the bulk of the algae taken by the ereen- 
winged teal, being found in 89 of the 96 stomachs which contained 
algae. All parts of the plant are eaten freely, but the ducks seem to 
be especially fond of the odgonia, very small spherical or egg-shaped 
objects which form part of the reproductive apparatus and are 
attached to the whorled leaves. They are usually coated with lime 
and are rather hard, and consequently often remain in the stomach 
after all other parts of the plant are digested. Stomachs were found 
containing thousands of them, and occasionally they constituted the 
total contents. Musk grasses, of which there are many species, have 
a very wide distribution, and have been found in duck stomachs from 
practically all parts of North America. | 
DUCKWEEDS (LEMNACEAE), 1.9 PER CENT. 
The duckweeds, the simplest and smallest of flowering plants, form 
a rather important element in the food of nearly all ducks which live 
on plant matter. These plants, at least in the typical genera, con- 
sist of merely a frond or leaf floating freely upon the water, with one 
or more small roots dangling below. The fronds are fleshy and 
tender, and are scooped up greedily by the ducks. They had been 
taken by 44 of the 653 green-winged teal examined, and averaged 
1.9 per cent of the total food. 
| WATER MILFOIL FAMILY (HALORAGIDACEAE), 1.11 PER CENT. 
_ The water milfoil family is represented in North America by three 
genera: Water milfoil (J/yriophyllum), mermaid-weed (Proserpinaca), 
and bottle brush (Hippuris). The seeds of all three of these were 
present in the series of gizzards examined. Water milfoil seeds had 
‘been eaten by 58 birds, those of bottle brush by 16, and those of 
mermaid-weed by only one. 
Antmat Foon. 
Insects formed 4.57 per cent of the total food of the green-winged 
teal, the remainder of the animal food consisting of mollusks, 3.59 per 
cent; crustaceans, 0.92; and miscellaneous, 0.25; the total amounting 
to 9.33 per cent. 
INSECTS (INSECTA), 4.57 PER CENT. 
The largest item of insect food eaten by these ducks was flies 
(Diptera), which constituted 2.07 per cent of the total. Nearly all 
of these were in the form of larvae or pupae, the adult flies seldom 
being caught. Probably those found had been taken from the sur- 
face of the water, as it does not seem likely that a duck would be 
