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), Orthoptera (grasshoppers, locusts, and crickets), Diptera 

 (flies), Hemiptera (bugs), Coleoptera (beetles), and Hymenoptera 

 (ants, bees, and wasps). Lepidoptera, Orthoptera, and Coleoptera 

 furnish the bulk of the insect food of birds. The lepidopterous food 

 is taken almost entirely in the larval condition, and comprises smooth 

 caterpillars belonging largely to the family Noctuidse, which includes 

 cutworms (see fig. 1), army worms, and their allies. The Orthoptera 

 eaten are pnncipally long- and short-horned grasshoppers (Locustidse 



Fig. 2.— Grasshopper (after Riley; 

 loaned by Division of Entomology). 



