A lot of years ago I used what were called Coyote Getters . They were a small single shot 38 caliber gun . The shells they used were 38's loaded with just enough powder to cover the primer then a light cardboard disk with sodium cyanide up to about an 1/8 inch from the top another disk then sealed with wax or a tar . You would rap the shell holder with wool , cotton ,or flannel . You had a stake that was driven into the ground , A hollow tube made out of electrical conduit that had a slit cut into it then rolled back and a small piece of spring wire soldered on it to hold the trigger of the getter in it the tube was mashed flat on one end you would put dirt or a piece of wood in the bottom of the tube so you could use a bolt to drive it into the ground without blowing the bottom out . You had a piece of 1/8 hard wire with a dimple drilled in one end and a loop on the other end you set the firing device on something hard then put the dimple on the firing pin pushed it down and set the trigger you then put it in the tube . Then you put your shell into the shell holder and screwed onto the gun . With it in place you then took your bait and put it on the top , shell holder, around the outside but not over the end of the shell . The old government guys had what they called getter butter or coyote butter . Some of it was made with bone meal as a base and some of it used blood meal as a base with some mineral oil or glycerin mixed in to make a smooth paste . They all had their secret ingredients they added to it that they clamed would make a fox or coyote slobber all over themselves just to get a bite . When you screwed the top on these things you wanted to wear a good heavy leather glove be down on your knees bent over facing away from them and reaching out to the side . When you went to pick them up out of the field you darn sure want to be in this position in case some thing had pulled on it but didn't set it just leaving it set with a hair trigger . You had the back of your hand facing you using your forefinger and thumb to screw the top on . If one went off doing either of these things it hurt like crazy when it hit the palm of your gloved hand and you for sure didn't want it to puncture your skin . When an animal pulled it they were scared half to death and would run as hard as they could as far as they could before they died . The first thing I would do was turn a circle looking for eagles or buzzards eating some thing . If I didn't see that I started walking circles at about 25 feet increasing distances un till you saw them . The farthest I found a coyote was close to 400 yards. I was up on the mountain one time fixing fence and found some of them with the tubes wired to fence posts a foot and a half off the ground at an upward angle . Winter sets for frozen ground and drifting snow . It's hard to say who put them there and how long they had been there they didn't work any longer and had been out lawed for years by then .