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.
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.
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.
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.