20 THE EELATION OF SPARROWS TO AGRICULTURE. 



occasionally inclndes snails or millipedes; insects — mainly grasshop- 

 pers, beetles, and caterpillars— constitute more than nine-tentlis. The 

 vegetable food is comiDosed almost entirely of seeds, althongh it also 

 comprises a small quantity of fruit. 



FOOD NEUTRAL IN EFFECT ON AGRICULTURE. 



The neutral part of this food is made up principallj^ of certain 

 insects, spiders and snails, a small amount of wild fruit, and some 

 seeds of useless plants. Insects form about four-fifths of the animal 

 matter of the neutral part, comprising ants and certain kinds of flies 

 and beetles. The flies, which are usually adult insects, but some- 

 times larvse, include midges (Chironomidse), flies related to the house- 

 fly (Muscidfe), March-flies (Bibionidje), and crane-flies (Tipulid^e). 

 These insects never amount to 1 percent of the volume of the entire 

 food of any species of sparrow for the whole jeRi\ May-flies (Ephem- 

 eridpe), emerging from the water by the million, are j)re3^ed on by the 



sparrows that dwell in the immediate 

 vicinity of streams or ponds. Ants sel- 

 dom equal 2 percent of the volume of the 

 year's food. Both tj'pical ants (FoVmi- 

 cidje) and myrmicids (Myrmicid^e) are 

 taken. Such ants as Formica fusca and 

 Jill' ^ H^^^^P "^^ F. suhsericia, Lasius, 2fyrmica, and 2>- 



■|,|. fi^^l^H //'a??ior/?f?7? are frequentl}^ selected. They 



are often eaten while yet in the winged 

 state and are then caught in the air. 

 Beetles of little or no economic imi^or- 



FiG. 11.— Dnng-beetle (ApJiodius) , 4_xr? o^-- -t- -p 



(loaded by Prof. s. A. Forbes). ^^^^^ amouut to froui o to percent of 



the total A'olume of the food for the en- 

 tire 3'ear. These are for the most part dung-feeding species belong- 

 ing to the genera Apliodius (see fig. 11), Af(enius, Onilwphagus, and 

 Hister. They are often found by hundreds in cow droppings in 

 pastures. 



The remainder of the neutral part of the food is made ui3 of spiders 

 and snails. Spiders, though predatory, have not as yet been classed 

 as useful, because, as alread}^ stated, as a group the}^ seem to destroy 

 about as many beneficial as injurious insects. The kind most fre- 

 quently eaten by sparrows are the running ground-si:)iders, which, 

 though x^robabh" more useful than harmful, are of too little imxDortance 

 to be classed otherwise than as neutral. They constitute 1 to 3 per- 

 cent of the food. A few snails are eaten. These are as a rule not 

 injurious; and though an exception should be made of, the pond snail 

 [Limncea), which acts as intermediate host to the liver fluke, a pest to 

 sheep raisers, probably very few if any of these are included among the 

 small number of snails actually eaten, and they may be disregarded. 



