278 USEFUL BIRDS. 
assistance from birds in our gardens than in our woodlands 
or tields. Nevertheless, the few species that follow the 
plow and glean among the various vegetables are of the ut- 
most value to the farmer, who in the ordinary course must 
depend largely on them to protect his crops from certain 
insects that are difficult of control. Cutworms, army worms, 
and cabbage worms are a few of the garden pests which are 
eaten by birds, and which birds might control if sufficiently 
numerous. The squash bug and the Colorado potato beetle - 
are two insects which are seldom eaten, or by but few birds. 
Many of the birds of garden and field may be brought to 
assist the farmer in his battle against weeds. A weed is a 
useful plant in nature, and fulfils its purpose by filling bar- 
ren or unoccupied soil with roots, preventing a waste of that 
most valuable fertilizing constituent, nitrogen, and adding, 
by its decay, to the amount of humus and plant food in the 
soil. In the garden and field, however, these wild plants 
are out of place, for the farmer wishes to cultivate the 
corn, the bean, the potato, or other useful plants and various 
grasses, all of which, if left to themselves, may be dwarfed, 
stifled, or replaced by a vigorous growth of weeds, which 
spring up unbidden from the soil. 
Dr. Judd tells us that a single plant of one species of 
weed may mature as many as a hundred.thousand seeds in 
a season; and if these were unchecked, they might in the 
third year produce ten million plants. In competition with 
this bewildering multiplication, the corn or the bean, the 
wheat or the rye, with their comparatively few seeds, must 
soon succumb. 
Constant use of the cultivator and hoe will do much to 
eradicate weeds from cultivated land, but they are always 
present in the grass field; and, as most of the grass is cut 
after the seeds have ripened, and fed to farm animals, there 
are always weed seeds present in the manure which is used 
in garden and field. Thus the farmer annually sows weed 
seed in his cultivated land. 
Even when the garden is kept clear of weeds, there are 
still weeds around the edges of fields and gardens, and along 
roadsides, ditches, and hedgerows, which continually seed 
