Wednesday, May 13, 2015

Rainbow Scarab

I learned about another new insect today! I saw this in our backyard. At first I thought it was one of those doggoned Japanese beetles (invasive pests), but it looked stockier and somehow didn't fit my "search image" for that species. And I was right!

May I introduce you to: a rainbow scarab!

Phanaeus vindex is apparently pretty common in the eastern United States, though I'd never seen one before.

It's a type of dung beetle--one of those scarabs that takes advantage of organic materials that aren't completely digested by mammals. Unlike other dung beetles, which are generally dull black (shiny black if they're exceptionally spiffy), this one is bright shiny green and copper!

Like other dung beetles, this species sniffs out piles of poop using its elaborate antennae (orange, here--with platelike segments that can be fanned out or pressed together at will). Once it catches a whiff, the beetle, buzzing heavily like a bumblebee, flies upwind to the source of the stench (you know, to dung beetles, poop must smell like a steak on a grill, or a bunch of pretty flowers, or a cherry pie in the oven).

Finding the poop, the beetle burrows under the pile, rolls some of the dung into a ball, then buries the ball in a hole beneath the pile, laying eggs on it. After hatching, the larval beetles (C-shaped grubs) eat the dung as they develop. (Like other beetles, the larvae then pupate, much like a butterfly, and emerge as a winged adult.)

Most dung beetles (quite famously) roll their little dung balls away from the pile of poop. If you haven't seen Zefrank's video "True Facts About the Dung Beetle," you must see it. I insist. But the rainbow scarab doesn't do that "rolling" bit.

It's ironic that this species, which is so beautiful, apparently spends more time completely under the dung than the dull black types, which roll the poop along like a circus act for all to see.

Another thing: this one I saw is a male. See the horn on the top of its head? Females don't have that. Apparently the horn plays a role in male-male competition.

Sometimes the horn on males is breathtakingly large. Look at Bugguide's Phanaeus vindex page for examples.

As I type this, Mr. Rainbow Scarab is probably forming himself a nice little poo-ball and looking to hook up with a girlfriend. I leave you with this closeup on his face. I can't help but see an "expression" in it, like "Aren't you about done taking pictures? Can I just leave now, please? I have things to do."

So, after harassing this beetle and taking a bunch of pictures of it, what did I do with him? I found a pile of cat poo in the backyard and set him down beside it. He immediately began digging into the soil next to it. Fascinating!

But I didn't stick around to watch--I was curious, but flies were buzzing around, and it didn't exactly smell like a bunch of flowers, either.

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