Friday, September 28, 2007

Necrophila americana

Last fall when my dad butchered a sheep, he dropped the pelt on top of the head, which he had left under a tree, and he forgot about it. A week later when he was passing by it, he grabbed the pelt, and under it was a perfectly clean sheep skull. Maggots could definitely not work that fast, so I asked a biology teacher who attends our church. He said it sounded like the work of a carrion beetle. After that, any time we came across a dead animal, we would put wool on top (to avoid predators or the domestic dogs finding out) and check on it a week later. I had never seen the creatures doing their work, since whenever I would check on the skeleton, the process was done.

Earlier today I was photographing a squirrel. After I was done, I turned around, walked two steps, and nearly stepped on another squirrel, except it was dead. Covering its opened wounds was the unmistakable American Carrion Beetle (Necrophila americana). These beetles are some of the best beetles for nature. As you can tell by the name, they eat carrion (dead animals). When an animal dies in warm weather, it immediately starts decomposing, releasing a stench that of course attracts flies (specifically, the big shiny green ones, Green Bottle Fly) and all sorts of Carrion and Burying Beetles. Judging by the disturbing view that I saw, they had just started on the squirrel, and they always start in the open areas.

I'm not sure entirely how long it takes for them to take care of certain sized animals. For each of the carcases that I have put out there for them, I would just go out a week later and find a perfect skull that was in need of dusting. For this dead squirrel that I found, I forgot to check on the carcass the next day, so I went out there two days after finding the body, to not find anything. If I had to guess, they finished their work quickly and cleanly, and some wild carnivore took the bones. I'm hoping that one day when I find them again, I can collect them and put them to work on a body in a certain protected area, and I can check on it daily to check out their work.

Carrion and Burying Beetles also help with the fly population. Obviously these beetles can just keep eating and eating. So the maggots that the flies leave on the bodies are competition. When the flies first lay the eggs (if you ever see sawdust looking stuff on something, they're fly eggs), the Carrion Beetles completely ignore them. Then when the maggots hatch and start devouring the meat, the Carrion Beetles start going for them too. I guess flies will just have to lay their eggs on things that Carrion Beetles can't get to.

This was all the information that I could gather on Carrion Beetles. However, if you find more information, please let me know, since I'm sure there's much more to discover!

So if you find a perfectly clean skeleton or skull, I'm sure you have the Carrion Beetles to thank for that!

9 comments:

ivy said...

I wonder if you put a carcase in a wire cage and leave it out, would that prevent scavengers taking off with your experiment?

Anonymous said...

That's a nice picture of the beetles, but I cannot tell how big they are. Are we talking bigger than a penny or smaller?

Katherine said...

Bigger than a penny. I'd say around nickel-size? It's still pretty small for eating carrion that fast. :-)

Anonymous said...

Any idea how much one can eat? Are beetles solitary like spiders, or do they have a hive/home somewhere?

Katherine said...

I do not know how much one can eat. I am hoping to find that out some day though! Like catch ten beetles, give them a carcass and weigh it every day to see how much they've devoured. And I think they're solitary. Something I'll have to look into. :-)

Anonymous said...

What would make a neat experiment would be to weigh a glass jar, then weigh your 10 beetles in the jar. Then weigh the carcass before you set them loose onto it. Each day you weigh the carcass, weigh the bottle with the beetles in it. The beetles might take 8 pounds off a 10 pound carcass, but I would be willing to bet that the beetles do not gain that much weight. Sound neat to you?

Katherine said...

That sounds very neat! I'll have to do that when I get my paws on the beetles. They probably won't gain any weight, but what happens to all the meat they devour? Ooo, this will some interesting experiment!

Anonymous said...

Just checking to see if you ever attempted this experiment?

Katherine said...

I'm actually planning to try the experiment this year. Because these beetles are so under-studied, I'll be sure to post the results. :-)