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FLYTRAPS. AND. THEIR OPERATION. 3 
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 there is little chance 
of the flies, once in, finding their way out again. This principle is 
modified to fit different conditions. For instance, the window 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 gar- 
bage cans; and the manure-box trap retains the flies bred from in- 
fested 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 lhght, 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. 
THE CONICAL HOOP TRAP. 
A trap which appears from extensive tests made by Mr. E. W. 
Laake and the author to be best for effective trapping, durability, 
ease of construction and repair, and cheapness may be made as follows: 
The trap consists essentially of a screen cylinder with a frame 
made of barrel hoops, in the bottom of which is inserted a screen 
cone. The height of the cylinder is 24 inches, the diameter 18 
inches, and the cone is 22 inches high, and 18 inches in diameter at 
the base. Material necessary for this trap consists of four new or 
secondhand wooden barrel hoops, one barrel head, four laths, 10 feet 
of strips 1 to 14 inches wide by one-half inch thick (portions of old 
boxes will suffice), 61 linear inches of 12 or 14 mesh galvanized screen- 
ing 24 inches wide for the sides of the trap and 41 inches of screening 
26 inches wide for the cone and door, an ounce of carpet tacks, and 
two turn-buttons, which may be made of wood. The total cost of 
the material for this trap. if all is bought new at retail prices, is 
about 65 cents. In practically all cases, however, the barrel hoops, 
barrel head, lath, and strips can be obtained without expense. This 
