CONTROL OF VERMIN 105 



it releases the bottom end of a vertical rod, which has a hori- 

 zontal extension from its top to block the door, as with 

 the other model. From the junction of the vertical with the 

 horizontal rod a spring is attached and to the back of the 

 trap. The bottom of the perpendicular rod has a tooth or 

 groove which is held by the spring against the pan. When 

 the pan is forced down the lower rod is released, so the 

 spring can pull back the horizontal rod and let down the 

 door. 



Pitfall. Another device which Evans uses along his wire 

 fence is a pitfall arrangement. A pit 4^ feet deep is dug 

 just outside the fence. Over the part closest to the wire is 

 a wooden covered passage. At each approach is a balanced 

 board weighted at the outside end. These boards meet in 

 the middle of the passage over the centre of the pit. The 

 animal gets past the divide and the board tips down and 

 drops the victim into the abyss, springing back into 

 place. Outside the passage the pit is boarded over by a trap- 

 door, through which to remove the captives. Some morn- 

 ings there are strange collections of uncongenials in the pit 

 cats, rats, skunks, and what not, too much scared to fight. 



Clover-leaf Trap. Another effective device, which might 

 be called the " clover-leaf trap," is used by Frank Hopkins, 

 A. G. MacVicar, and others. It is a wire mesh labyrinth, 

 in the shape of a four-leaf clover, the lobes almost meeting in 

 the centre. At the bottom of one of these indentations 

 there is a small opening at the ground, just large enough to 

 admit whatever vermin or birds one expects to trap. It 

 need be only 2 feet high and about 6 feet across, the wire 

 being held in place by small stakes. It is covered on top, 

 but has there a door, through which to reach captives. Bait 

 is put inside, and for birds a trail of grain is laid to the en- 

 trance. The victims enter readily, but seldom discover the 



