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FLIES AS A NATURE-STUDY PROBLEM 



91 



attracted to it and does not feed the flies and let them go ; to have 

 also some device — like the net described below or something 



better — to insure easily picking up 

 stragglers that escape the traps, and 

 would otherwise keep up the egg laying 

 and prolong the fight indefinitely. 

 This plan may be carried into effect 

 any time during the year when the flies 

 are active, in spring or summer or 

 early fall. Late in the fall flies become 

 sluggish, are not hungry and, hence, 

 are not easily attracted to baits and 

 are chiefly concerned in crowding into 

 houses for warmth and protection. 

 It is best to begin as soon as flies 

 FlG appear in the spring, be sure that every 



home is supplied with traps and nets 

 in good season, and continue as long as any flies are emerging from 

 winter quarters or hatching out of the barnyards. Flies emerge 

 from winter quarters hungry and if traps at this time are prop- 

 erly managed, very little will remain to be done with nets or 

 swatters. 



The Traps. The principle upon which fly traps are made is that flies tend 

 strongly to crawl upward toward the light, especially after feeding. (When 

 seeking food or a place in which to oviposit, they may crawl downward into 

 dark cracks.) Hence by arranging cracks and holes in screen wires which 

 open upward, we can make a simple and effective fly trap of any size we wish. 

 The trap described below was first designed to fit in a stable cellar window, 

 the window in some sunny corner out of the wind, where all the flies of the 

 barnyard tend to congregate. In this position the trap-folds in the sides do 

 practically all the work. In case of a tight stable, with sacks hung over all 

 the other windows — to darken them and flap in the wind — sooner or later 

 every fly will attempt to go in or out of the trap window and be caught coming 

 or going, stable flies horn, black and even bot flies and mosquitoes, that are 

 not attracted to baits, and if the window trap is well baited, we may establish 

 a whirlwind focus for house and blow flies as well. If the stable is open and 

 full of cracks, the trap should be made without bottom board and set over a 

 ridge of attractive bait on the manure pile, or in the most likely place in the 

 barnyard. It is well to plan traps to take wire screen of standard widths — 

 24 inches wide by 30 inches high and 12 inches thick is a good size for a large 

 dairy or farm barnyard, and it is well to have two trap folds on each side, 

 one about the middle and the other about three inches from the top. The best 

 size for house-yard is 12 inches wide and high and 10 or 12 inches thick, and 

 with waste box lumber a boy can construct this at a cost of about $0.07 

 worth of screen wire. 



Fig. 6 gives steps in making the traps taken from actual specimens in a 

 manual training class. The rule in making is first to cut out all the pieces. 

 Then every notch and cut can be made to fit its proper piece. The parts go 



