4 Farmers' Bulletin 73^. 



ter. In the latter group the house % - is b}^ far the most important. 

 The stable fly is strictly a vegetable breeder, as are also certain other 

 species which occasionally come into houses and in rare cases may 

 contaminate foodstuffs. The stable fly,^ which breeds in cow manure 

 or decaying vegetable matter, and the horn fly,* which breeds in 

 manure, are blood-sucking species, and can be caught in ordinary 

 flytraps in comparatively small numbers only. The kind of flies 

 caught depends to a considerable extent on the material used for 

 bait. In general the house fly and other species which breed in 

 vegetable matter are attracted to vegetable substances, while the blow- 

 flies will come most readily to animal matter. This rule, of course, 

 is not absolute, as flies are less restricted in feeding than in breeding 

 habits, and, as is well known, the house fly is attracted to a greater 

 or less extent to any moist material, especially if it hasi, an odor. 



TYPES OF TRAPS. 



The same general principle is involved in nearly all flj'traps in use, 

 though superflcially they may appear quite different. The flies are 

 attracted into a cage, as it were, by going through a passage the 

 entrance of wliich is large and the exit small, so that there is little 

 chance of the flies, once in, finding their way out again. This prin- 

 ciple is modified to fit different conditions. For instance, the win- 

 dow trap, devised by Prof. C. F. Hodge, catches the flies as they 

 endeavor to enter or leave a building; the garbage-can trap, for 

 which Prof. Hodge is also to be credited, catches the flies that have 

 entered garbage cans; and the n>anure-box trap retains the flies bred 

 from infested manure put into the box. 



The attractant used to induce flies to enter traps may consist of 

 (1) food, as in baited traps; (2) odors, as in window traps placed in 

 windows from which odors are emitted; and (3) light, as in traps 

 on manure boxes. Of course, light is an important factor in the suc- 

 cess of all traps, for, as is well known, flies have a marked tendency 

 to go toward the light, and they usually enter the trap by flying 

 toward the light after having been attracted beneath it by bait or 

 after entering a room in search of food. 



CONICAL TRAPS 



A number of traps of this general type are on the market, but most 

 of these are of small size. Nearly all are constructed with a dome 

 instead of a cone, and on this account the catching power is reduced 

 about one-third. Moreover, the farmer, dairyman, or anyone with a 

 few tools can construct traps at a small fraction of the sale price of 

 ready-made ones. 



-Vii-scu <l()in('f!tic<i L. ^ 8tomox!/s cahitran.^ L. * L}ipero.iia irritnns L. 



