Friday, July 6, 2012

Invasion of the longhorns

My, what a big set of antennae you've got, Ms. Beetle! Elegant and outrageous, a Dectes texanus longhorned beetle explores a leaf in Adams County. I made this image on August 27, 2011. This rather amazing bug has no common name, rather amazingly. It and its closely related ilk are collectively known as flat-faced longhorns.

Over 20,000 species of longhorned beetles have been named worldwide, and there are probably thousands of species yet to be described. The adults are often fabulous looking creatures, with their incredibly long antennae perhaps the most distinctive feature. When a longhorn alights near someone, they're sure to notice it. The problem is, for longhorned beetle enthusiasts, they're mostly out of sight for much of the year. Nearly all of the species spend much of their life cycle as a grub, happily boring through the inner tissues of plants. You'll never, or at least hardly ever, see that stage. But for an all too brief glorious period, the adults emerge from the wood and take flight as they seek mates and sustenance from flower nectar.

Most years, I'm lucky to run across a small handful of longhorned beetles, if that. So it was with a fair bit of shock and joy that I glanced down into the snakeroot on a recent field trip in southern Ohio and saw this magnificent beast. It is a six-banded longhorn beetle, Dryobius sexnotatus, and it is said to be rather rare.

This is a big beetle, probably over an inch long, and you wouldn't have missed it. Bold yellow and black patterning certainly doesn't make it blend with its surroundings, and it seems likely that the six-banded longhorn is a hornet mimic. Lots of would-be predators will leave an insect with this sort of warning coloration and patterning well enough alone.

Our discovery of this beetle came at the conclusion of a long, very hot field day, and that feeble excuse is my rationale for not making better photos. The beetle was very active, and in dense shade, hence the lack of crispness. I should have taken the time to employ some tricks of the trade to get better images.

The six-banded longhorn rapidly scales a sugar maple, which is said to be one of its host trees, along with beech and elm. There were plenty of these trees in the immediate vicinity. Six-banded longhorns have generated more than the average interest among longhorned beetle enthusiasts because they are thought to be rare. Some authorities state that they are typically associated with older-growth forests, but this one wasn't - it was in a rather typical area of varied tree succession, with only patches of larger older woods.

A few days back, a friend posted this photo on Facebook, asking for an identification. The beetle had by turns horrified and fascinated the people who discovered it on this poolside post. Donald the Birder was first with the identification: the multisyllabic Elytrimitatrix undata, yet another spectacular longhorn with apparently no common name. By this point, I had received probably three or four other requests for information about longhorned beetles from various people, which is WAY more than a normal year.

One or two nights after the Facebook beetle post, I got in my car which had been sitting in my driveway with the windows down. Lo and behold, no sooner had I dropped behind the wheel when a suspiciously long antenna poked out from behind the sun visor, and out came a big longhorn! It was dark, and viewing was not great, but I am reasonably sure it was also the clumsy-to-say Elytrimitatrix undata. It scampered to the window and whirred off into the darkness before I could capture it for closer study and possible photos.

Then, just yesterday, Bernie Master noticed an interesting bug on his purple coneflower and managed an image before the thing got away. Voila! Yet another longhorn, this time the supposedly common and widespread banded longhorn, Typocerus velutinus.

Maybe all of these longhorned beetles coming to my attention is just coincidence, but it's way more longhorn action than I normally detect in a season. Most sources seem rather general when describing host species for the three species above; "hardwoods" is a typical but very generic descriptor. As wood-boring beetles often attack the softening tissues of dead or dying trees, I am wondering if the glut of ash trees that have succumbed to the emerald ash borer is producing a bumper crop of longhorned beetles.

If you've seen any longhorned beetles, or have insights into whether this truly is a boom year for them, let me know.

Perhaps it will also be a great year for this longhorned showstopper, the utterly amazing Amorpha borer, Megacyllene decora, which is widely considered to be the world's most spectacular insect. I think this one truly is rare, at least in these parts. The date of our 3rd annual Great Amorpher Borer Expedition will soon arrive, and I greatly look forward to that. For an account of last year's expedition, CLICK HERE. Hopefully expedition members will find many of these showy tangerine beasts.


Sharkbytes said...

Beautiful insects!

Anonymous said...

Well i found one in my dogs water and was curious to find out what it was and thanks to this i found a pic of the same one it is one one of the sixbanded ones it is rather pretty

J. Morgan said...

I recently found a bunch of these 6-banded beetles in a tree that fell. I took some pretty good pics. Not sure if you can see this on on Facebook: - They are definitely a eater of wood. Jason