2 Farmers' Bulletin 73i 



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 

 blowflies 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 Imown, the house fly is attracted to a 

 greater or less extent to any moist material, especially if it has an 

 odor. 



TYPES OF TRAPS 



The same general principle is involved in nearly all flytraps in use, 

 though superficially they may appear quite different. The flies are 

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

 entrance of which 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 Professor Hodge is also to be credited, catches the flies that 

 have entered garbage cans ; and the manure-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 Avindow 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. 



There are now being made by certain firms in the Southwest traps 

 of the dimensions and with the desii-able features discussed in the 

 following pages. These traps are all metal and some are built so 

 that they can be taken apart for shipment. 



THE CONICAL HOOP TRAP 



A trap which appears from extensive tests made by E. AV. Laake 

 and the writer to be best for effective trapping, durability, ease of 

 construction and repair, and cheapness may be made as follows: 



* JIaematohin irritnuft },, 



