Food BENEFICIAL IN EFFECT ON AGRICULTURE. 27 
sparrow, junco, English sparrow, tree sparrow. Gambel's sparrow, 
and white-throated and white-crowned sparrows. 
Among the weeds which are troublesome in fields, especially among 
hoed crops, may be mentioned ragweed (Ambrosia artemisia? folia), 
several species of the genus Polygonum — including bindweed (P. con- 
volvulus), smartweed (P. lapathe folium), and knot weed (P. avicu- 
— pigweed (Amaranthus retrofleacus, and other species), nut-grass 
and other sedges (Cyperacece), crab-grass (Panicum sanguinale) and 
some other varieties of panic-grass, pigeon-grass (Chcetocha viridis 
and ('. glauca), lamb's-quarters {Chenopodium album), and chick- 
weed (Alsine media). Every one of these weeds is an annual, not 
living over the winter, and their seeds constitute fully three-fourths 
of the food of twenty species of native sparrows dining the colder 
half of the year. Prof. F. E. L. Beal, who has carefully studied this 
subject in the upper Mississippi Valley, has estimated the amount of 
seed eaten by the tree sparrow, junco. and other sparrows that swarm 
down from Canada in the fall and feed in the rank growth of weeds 
bordering roadsides and cultivated fields. He examined the stomachs 
of many tree sparrows and found them entirely filled with weed seed, 
and concluded that each bird consumed at least a quarter of an ounce 
daily. Upon this basis, after making a fair allowance of the number 
of birds t<> the square mile, he calculated that in the State of Iowa 
ah me the tree sparrows annually destroy 1,750,000 pounds, or about 
875 tons, of weed seed during their winter sojourn. 1 The value of 
this work can best be appreciated by considering the annual loss to 
the farmer occasioned by the presence of weeds and the consequent 
reduction of cultivated crops. Mr. F. V. Coville, botanist of the 
Department of Agriculture, states that i; since the total value of our 
principal field crops for the year 1893 was $1,-760,489,273, an increase 
of only 1 percent, which might easily have been brought about through 
the destruction of weeds, would have meant a saving to the farmers 
of the nation of about -S17, 000,000 during that year alone.'"- 
Besides tree sparrows and juncos, the most important sparrows that 
destroy weeds in the Mississippi Valley and on the Great Plains are 
the fox sparrow, the snowflake, the white-crowned sparrow, Harris's 
sparrow, and the different longspurs. Farther south are found the 
lark sparrows, and on the Pacific slope occur Xut tail's sparrow, the 
golden-crowned sparrow, and Townsend's sparrow. East of the Alle- 
ghenies the most active weed eaters are the tree sparrow, fox sparrow, 
junco. white-throated sparrow, song sparrow, field sparrow, and chip- 
ping sparrow. On one of the Maryland farms visited in 1890, tree 
sparrows, fox sparrows, white-throated sparrows, song sparrows, and 
juncos fairly swarmed during the month of December in the briers 
of the ditches betweeu the cornfields. They came into the open 
farmers' Bull. No. 54, U. S. Dept. Agriculture, p. 2s. 1897. 
- Bull. No. 17, Div. Botany. U. S. Dept. Agriculture, p. 3. Is96. 
