. Bulletin - Biological Survey. Zoology, Economic. THE EELATION OF SPAREOWS TO AGRICULTURE. ::!:iiiiii Hfillli. Fig. 1.—Cutworm and moth (after Howard loaned by Division of Entomology). The seed element is of particular interest onh^ when it shows destruction of grain or weeds. Injury to grain or fruit hy birds is usually the most prominent and often the only fact of economic ornithology^ possessed b}^ the layman; yet comparatively few birds harm either of these crops, while manj^ species render important service to agriculture by destrojang weed seed. As has been aptlj^ said, a weed is a plan
. Bulletin - Biological Survey. Zoology, Economic. THE EELATION OF SPAREOWS TO AGRICULTURE. ::!:iiiiii Hfillli. Fig. 1.—Cutworm and moth (after Howard loaned by Division of Entomology). The seed element is of particular interest onh^ when it shows destruction of grain or weeds. Injury to grain or fruit hy birds is usually the most prominent and often the only fact of economic ornithology^ possessed b}^ the layman; yet comparatively few birds harm either of these crops, while manj^ species render important service to agriculture by destrojang weed seed. As has been aptlj^ said, a weed is a plant out of place. Certain plants seem to have formed a habit of constantly getting out of place and installing them- selves in cultivated ground, but whether actually among crops or in adjacent waste land, from which they c|in spread to cultivated soil, thej^ are alwaj^s a menace. In the garden they occup}^ the room allotted to useful plants, and ap- propriate their light, water, and food. Any check on these nox- ious interlopers, a million of which can spring up on a single acre, will not only lessen nature's chance of populating the soil with worse than useless species, but will enable the farmer to at- tain greater success with cultivated crops. The hoe and cultivator will do much to eradicate them, but some will always succeed in ripening a multitude of seeds to sprout the following season. Cer- tain garden weeds produce an incredible number of seeds. A single plant of one of these species, as purslane, for instance, may mature as mau}^ as 100,000 seeds in a season, and these, if unchecked, would produce in a few j^ears a number of weeds utterl}^ beyond compre- hension. The habits of some of the common weeds are considered in connection with the discussion of the value of birds as weed destroyers (see pp. 25-28). The animal food of the smaller land birds consists of insects and spiders. The insects belong for the most part to the orders Lepidoptera (butterflies and moths),
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