The Horned Passalus and Its Passengers

                               I think of this as my Summer of Bugs. I've always liked bugs.


But this year, I have tools to learn more about them, and I am using those tools. My favorite is Eric Eaton's and Kenn Kaufman's Field Guide to Insects of North America. There, I learned that what I've always called a Betsy Bug is a Horned Passalus (oh wonderful name!) Odontotaenius disjunctus.  It's a pretty wonderful bug, I must say.  There are only two species of passalid in North America; it's a mostly tropical family, with over 500 species worldwide. Shiny (Patent Leather Beetle is another colloquial name), strong (just try holding one back!) and robust, it's very beautiful and strange to watch as it feels its way around with jointed antennae. Like roaches, the passalus is sensitive to air currents, and rather shy. It's usually found in rotted wood, which it eats. But unlike termites, for instance, it lacks beneficial bacteria in its gut to digest the wood. So it eats the wood, poops, and then eats the fungus that grows on its own poop. Now what is not to love about that?

But it gets better. The Horned Passalus is a social insect, and Eaton says that it is able to "talk" to its family (yes, it has a family; we'll get to that) by rubbing bits of itself together, something called stridulating. And curious entomologists have identified fourteen different sounds, or calls, that this insect can make.

See the cool little horn on its head?

I was bitten pretty good by a Betsy Bug while playing in a Virginia sandbox at the tender age of six or so. To be fair to it, I was squishing it in my hand. I didn't mean to; I thought it was a sand clump. They don't usually bite, though. They're too busy being cool. Get this:  They chew through rotted wood, making galleries where they haul around their eggs and larvae, a bit like giant ants. They live in colonies with their offspring. They pair up. And the pairs of beetles care for their larvae, feeding them chewed wood mixed with their own feces (there they go again!) They can live up to 16 months, and most of that is spent in caring for their young while the eggs hatch, larvae grow and metamorphose into pupae and then adult beetles.

I like the golden leg fringe bling. Not sure what its function may be; maybe it acts as a comb to keep wood debris off its limbs? Maybe it combs those sensitive antennae with its leg fringe? I would need to watch one for a few hours to see what it does.

My partner in discovery is my Canon G-11. (Who knows how many of these cameras I've sold? B & H Photo's link that was supposed to kick back $$ never worked for me, so heck with it. Go buy one. Tell 'em I sent you). 

This little camera shows me things I can hardly see with my own orbs. See anything interesting on the beetle's head? Yeah, me too. Mites. Little copper-colored round mites.

I noticed that this beetle (I have two individuals in these shots) was carrying mites, and it seemed to have little scooped-out areas on its head that cradled the mites just so, which got me thinking that the mites might be doing something nice for the beetle; maybe cleaning its jaws and keeping it all shiny-polished; maybe getting rid of excess food or feces; maybe singing tiny little mite songs to it as it chews away on the rotten wood. Hi ho, Hi ho, it's off to work you go! Tra la la la! Hey, if a beetle can have at least 14 different calls, mites should be able to sing.

Some of the mites found on bess bugs are found nowhere else.

So something's going on here; the mites get something from the association with the passalus that they can't get anywhere else. Who knows what the passalus gets from it? That's bugs for you. Looking closely can lead to looking more closely, and then a question mark forms over your head that is pretty much permanent, like a halo.

 

I would much rather have a question mark over my head than a halo. Much more fun.