Backyard Biology

Nature stories from my backyard and beyond

Nature Activities

Trapping Carrion Beetles

Tuesday, September 6, 2011

The American carrion beetle (Necrphila americana) is one of our largest and most handsome beetles. Once seen, they are not likely to be forgotten. The problem is most people never see them. So, if one wants to locate a carrion beetle, how might one go about it? Of course it would help to know a little about the beetles’ habits, such as where they like to hang out.
Carrion beetles, as the name suggests, like to hang out on carrion - dead animals. Carrion beetles eat dead animals and raise their young on dead animals. So, a good place to look for carrion beetles is on a dead animal. However, one does not often come across a dead animal in one’s wandering through the woods. The competition for dead animals is high, they often get swallowed up by crow, foxes or other large predators before the carrion beetles can find them.
If you come across a dead animal - mouse, bird, frog or other animal of that size, and you want to save it for carrion beetles, here is a suggestion. Place an empty milk crate upside down over the animal and weigh it down with rocks. This will prevent large predators from carrying it off while allowing smaller animals like the carrion beetles access to it. Check on it daily to see if you have lured in a carrion beetle. Carrion beetles feed during the day, so no need to check it at night.
Occasionally, you might find the milk crate to be empty of the dead animal, but seemingly undisturbed by a large predator. It is possible that the dead animal was visited by a pair of burying beetles, who also feed on and raise their young on dead animals. Burying beetles, active at night, bury their dead animal a couple of inches under ground, where they can feed and raise their young in privacy. So how can you tell if your dead animal was buried by a burying beetle? Before you cover it with the milk crate, tie a foot-long piece of light string - such as dental floss - to one leg. If, when you check your milk crate, you find the string partly buried, you know that burying beetles have been at work.

If you don’t happen across a dead animal, you might want to bait your trap with a substitute dead animal, like a chicken leg or piece of fish. You can try the same technique - placing a milk crate over it. Another suggestion is to put it in a suet feeder and hang it from a bird feeder pole. This has the advantage of keeping it away from larger ground dwelling predators and makes it easy to observe. I have set one of these up just outside my kitchen window where I can easily view it. The problem is, as you can imagine, that after a while the odor of rotting meat enters the house every time I open the window.

I recently read that carrion beetles are attracted to a 45% solution of isopropyl rubbing alcohol and can be used as a lure in an insect Trap. I can’t wait to try this. I will place it right outside my kitchen window. I’d much rather smell rubbing alcohol than dead animals any day.

 

Materials

  • Plastic jar (2 liter soda bottle or juice container)
  • pill bottle
  • cotton clothes line
  • rubbing alcohol
  • water
  • measuring cup
  • 1/4 inch drill bit and drill
  • sharp knife

Instructionssoda bottle

  1. Cut three 1” holes in the side of the bottle - equally spaced around the bottle













  2. Drill a 1/4 inch hole in the top of the pill bottlepill bottle

  3. Insert a piece of clothes line through the hole leaving about 1” projecting above the cap.











  4. Drill two holes opposite each other near the bottom of the baker trapbottle and insert a piece of clothes line through one of the holes and tie a knot in the end that is inside the bottle. Then nsert the other end of the clothes line through the other hole and tie a knot on the end inside the bottle. This piece of clothes line will be used to hang the bottle upside down.

  5. Make a mixture of 45% isopropyl rubbing alcohol by adding 1/4 cup of water to 1/2 cup of alcohol.

  6. Fill the pill bottle with the alcohol mixture and attach the pill bottle to the inside of the plastic bottle.

  7. Hang in a shady area.