Monday, August 23, 2010

The Great Borer Expedition

The marina at Shawnee State Park, Scioto County, Ohio. May not look like the most exotic locale in the world, but as we shall see, there are some very interesting critters to be found here. This is Ohio's Deep South; as far as one can move towards the equator and not dip their toes into the Ohio River. In fact, the marina is on our mightiest stream; the one that separates us from neighboring Kentucky. And a number of plants and animals reach the northern limits of their ranges in the Ohio River Valley.

Last year, John Howard and I were exploring here when we encountered one of the most magnificent beetles I had ever laid eyes on. John, who lives in the area and explores Ohio River habitats all of the time, had only seen it once, a few years prior. He took photos, but was unable to pin a name on the beast as it wasn't in any of his books or easily findable on Internet resources. Finally, I posted one of my photos to BugGuide.net and was rewarded with a quick reply - Amorpha Borer, Megacyllene decora.

The gentleman who provided the answer was none other than Eric Eaton, and he reported that he had seen but one despite living in Cincinnati for eleven years. By now, I was consumed with interest in this seemingly exotic bug, and we began plotting out an expedition to find more of these beetles in 2010. Last Sunday was the fateful day.

This insect will offer a suggestion of the showiness of our quarry. It is a Hickory Borer, Megacyllene caryae, which can be locally abundant in spring. Like other beetles in the genus Megacyllene, it is an apparent hornet mimic.

You may have seen this one - it often is found seeking nectar on goldenrod flowers from about now through fall. It's the Locust Borer, Megacyllene robiniae, another nice-looking bug. Still, it holds no candle to our quest beetle; the object of the chase of what may to date be the world's only Amorpha Borer Expedition.

Were we successful? You bet your longhorned beetle we were! Here it is - the dashing Amorpha borer, Megacyllene decora. What a bug! Even a beetle-hater would like it. Large and tinted in the most beautiful hue of orange-yellow imaginable, this black-dashed stunner inflames the passions of all who see it, and upon discovery some of our party were rolling on the ground in fits of rapturous ecstacy.

OK, maybe no one got quite that excited but we were pleased as punch to successfully score the beetle. Actually, the group was rather displeased with me soon after the first beetle was found. I spotted it nectaring on some Giant Goldenrod, Solidago gigantea, and demanded that the net be turned over to me. I took a clumsy swipe and whiffed, the beetle escaped, not to be seen again and before any photos of substance could be made.

But the expedition's greatest success was yet to come. Stumbling somewhat dejectedly over to the aforementioned marina, it didn't take long before Janet Creamer found our target. This beetle, which proved to be far bigger and better looking than the one that I scared off, was quite cooperative. Scores of photos were made, and the group was able to fawn over the Amorpha Borer for quite some time.

There are some essential botanical ingredients required for this beetle, it appears. One, its host plant, False Indigo, Amorpha fruticosa. This small woody shrub occurs sporadically along the bank of the Ohio River, and the river bank may be the only Ohio locale for the plant in its native range (False Indigo has spread far to the north as a weed). The beetle lays its eggs in False Indigo and the beetle grubs bore their way around in the tissue.

When the adults emerge, they seem to stay in the immediate proximity of the False Indigo plants from which they were spawned. At least the females seek nectar and they definitely have a taste for Late-flowering Thoroughwort, Eupatorium serotinum, which is the plant in the photo above. They'll also use goldenrods but few of those are in bloom in this habitat this early in the season. Find these plants growing together on the banks of the Ohio River in August, and you may have a decent shot at discovering this splashy insect.
Janet eventually captured the Amorpha Borer and it didn't take kindly to being fondled. Here, it attempts to rasp off her flesh with those formidable mandibles. The black triangular mark on the thorax isn't typical - usually there are black stripes that band this region. I think some of the orangish pubescence may have rubbed off, exposing the shiny shell underneath.
The bold members of our Amorpha Borer Expedition (L to R): Ned Keller, Janet Creamer, John Howard, Tricia West, Cheryl Harner, Kathy McDonald, Debbie Wolterman. Your narrator was made to take the photo and thus couldn't be in the photo.

I love stuff like this. Finding some bizarre new animal that no one seems to know much about, figuring out at least the basics of its life history and successfully finding more of them. I'd love to know more about Megacyllene decora if anyone, anywhere, who might stumble across this knows something of the beetle. Who knows, there may be some place they are common as dirt and slapped away like offending mosquitoes. I doubt it, though.

Thanks to my fellow expedition members for their bravery and hard work in seeking the Amorpha Borer.

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3 comments:

Scott said...

Cool beetle! Good crowd of folks along on that as well. Looks like it was fun.

beetlesinthebush said...

This species isn't encountered commonly in Missouri, either. I have seen good numbers in the big river valleys in fall on goldenrod and snakeroot flowers - Amorpha is abundant in these areas.

One time I found a small stand of Amorpha in a prairie in western Missouri, cautiously inspected up and down the stems, and was fortunate to see an adult female crawling on the stem (presumably looking for oviposition sites).

It is indeed a spectacular species.

Derek Hennen said...

I just took a closer look at your 2nd picture of the borer, and it looks like there's a crab spider in the flower above the left antenna. Never know what you'll find when you look closely!