Carrion Beetle Mites
Here is the same carrion beetle, Nicrophorus tomentosus, from yesterday, but this time on its back. YIKES! What are all those bugs?!?
They are not its young. Those are parasites.
That’s a pretty severe infestation, isn’t it? These mites are phoretic parasites, meaning they cause no harm to the beetle; they’ve just climbed aboard for a ride. But even still… I’ve seen bugs climb aboard other bugs before. Normally it’s like five or six mites on a beetle. How come so many mites climbed aboard that one beetle? And how come the beetle let them climb aboard without preening them off?
I told you this bug was so cool it needed two days on the site….
Okay, so let’s review: this is a beetle that cannot reproduce unless it finds the corpse of a small dead animal. How often do YOU find dead animals lying around? Furthermore, the beetle has to be the first on the scene at the corpse: other carrion eaters may be eating the corpse, and other insects may have already colonized the body. The newlywed beetles will bury the corpse to protect it from other predators. But what if another insect has already laid eggs on the body?
Like flies. Flies are much more mobile than carrion beetles, and they can smell the carrion too. Furthermore, it takes up to 24 hours for the beetles to get the corpse properly buried. The opportunity for a fly to lay eggs on the corpse are pretty good. Fly maggots can overrun a corpse and severely reduce the survivability of the carrion beetle’s brood. Things look pretty grim indeed for our friend the carrion beetle.
Guess what those mites like to eat?
Phoresy means using another animal for transportation in a way that doesn’t harm the host. But those mites aren’t just riding the bus. They’re riding the lunch bus. They eat the fly eggs and even newly hatched fly maggots, and leave the beetle eggs and larvae alone. Then they move on, looking for another passing beetle to take them to another carcass.
This has to be one of my all-time favorite pictures from this site now, because when I first flipped that beetle over I went “Uaaahhhhh! GROSS!”… and then when I found out what was going on, I cried, “HOW FREAKING COOL IS THAT?!?”
Slowly getting the site back onto an even keel. It's nice to get back into the old posting rhythm.
tceisele said,
November 7, 2007 @ 9:35 am
How cool is that? That is very cool. Unfortunately, the sexton beetles I found working a dead mouse on the basement stairs a while back didn’t have any mites with them that I could see. Although, some years ago I did see two sexton beetles in the yard that played footsie for a while, and there were mites jumping off of one and transferring to the other.
Incidentally, Bug Guide has your pictures indexed under Nicrophorus tomentosus, not Nicrophorus tomentus, just in case people were having trouble looking it up.
AJ said,
November 7, 2007 @ 11:38 am
Carrion beetles are now my new favorite insect!
David Scott said,
November 8, 2007 @ 4:01 am
Love this stuff. I once captured a large slug to be the mascot for the Volksmovie Movement, which I was trying to promote at the time. I video taped the critter, and only then did I discover that it had parasites. Tiny white mites that could move like a halucination, seemingly swimming in the slug slime. I never checked them out any further, and don’t know whether they were simply parasitic or phoresy or symbiotic. But I was sure intrigued to see them.
I don’t know if this is accurately quoting Jonathan Swift but…
Big fleas have little fleas Upon their backs to bite’em. And little fleas have littler still, And so,ad infinitum.
It’s a wonderful, magical world. Thanks for the reminder.
Kit said,
November 8, 2007 @ 5:44 am
Wow, nature is amazingly cool sometimes!
David Brady said,
November 8, 2007 @ 10:00 am
David Scott: Cool story! Thanks!
AJ: THAT’S a sentence I didn’t think I’d ever hear. …let alone agree with.
Athena said,
November 8, 2007 @ 1:03 pm
Crazy! I think that picture belonged in with the Halloween stuff tho… heh. I guess not so much now that I know they weren’t *eating* the beetle. heh But boy, it *looks* disgusting/disturbing. LOL
David Brady said,
November 8, 2007 @ 4:19 pm
Hehe, yeah… I would have run it that week, except that I didn’t take this picture until November 3rd.
Joseph said,
November 9, 2007 @ 1:47 pm
Ooh! I’ve seen similar mites before on a giant water bug.
David Brady said,
November 9, 2007 @ 2:08 pm
Joseph: WOW! Is that your picture? That would make a great insectpod post, is all I’m saying….
David Scott said,
November 10, 2007 @ 3:36 am
Well, if yoiu liked the story, here a picture. Digging around in my archives I actually managed to find a picture of that slug that shows a louse. Here it is. http://www.themaninchina.com/sluglouse.htm