Friday, October 12, 2012

Black Witch spawned in Ohio!

Black Witch moths, Ascalapha odorata, draw attention wherever they occur. Even in the core of their range, which extends from Brazil north to south Texas and Florida, they seldom fail to elicit a reaction. These giants of the Noctuid Family can have a wingspan that reaches seven inches. They're the size of bats, and when one turns up under the eaves, people notice.

Black Witches are well known for their northward wandering. Individuals routinely move far north of their regular haunts, but extralimital records become increasingly scarce as one moves northward. Still, a few are found in Canada every year, and the record for the northernmost Black Witch comes from Churchill, Manitoba on Hudson Bay - the Polar Bear capital of the world. These large moths are obviously powerful flyers, and can  cover a lot of ground, fast. Sometimes large movements are associated with severe storms such as hurricanes. In July 2003, hundreds if not thousands of Black Witches were observed making landfall in coastal Texas after apparently crossing the Gulf of Mexico, pushed by the hurricane.

Here in Ohio, near the northern limits of their wanderings, the Black Witch is a great rarity and they are nor reported every season. This year has been exceptional, though - I think I've heard about five or six records. But the one reported below takes the cake.

 Photo: Omar Baldridge

I received this photo and two others courtesy of Omar Baldridge of Wheelersburg, Ohio, which is in Scioto County along the Ohio River. He stepped outside his house on the evening of October 5th, and was stunned to find this behemoth of a moth on his porch. When I saw Omar's photos, I was equally stunned, in part because it was a Black Witch, but even more so because the animal was obviously freshly emerged from its cocoon and hadn't even finished fully expanding its wings.

Given the juvenile condition of the moth, it had to have been spawned locally - very locally. Insofar as I am aware, there are no breeding records of Black Witch north of Texas. I sent the photos along to Dave Horn, OSU entomologist and president of the Ohio Lepidopterists, and he checked with Black Witch expert Mike Quinn of Austin, Texas (see Mike's comprehensive Black Witch website HERE). He didn't know of any reproduction records anywhere near this far north, but did mention that lepidopterist Steve Passoa once caught a female Black Witch in Columbus, Ohio, and was able to induce it to produce eggs.

As most of the northern records seem to be females, and given that these moths can probably reach Ohio in fairly short order, I suppose it shouldn't be utterly unexpected that this tropical moth could reproduce here.

Photo: Omar Baldridge

As the night wore on, the moth's wings increasingly expanded and gained form. Note the beautiful violaceous tint to the underwings. I've seen a number of Black Witches, but never the underwings. When fully mature, these moths always perch with wings spread on a flat plane with only the dorsal (top) surfaces visible. CLICK HERE for photos of another Ohio record of Black Witch that show the moth in typical repose.

Host plants for the Black Witch are woody plants in the Fabaceae, or Legume Family. Potential candidates that occur in Ohio are Kentucky Coffee Tree, Gymnocladus dioicus, Black Locust, Robinia pseudoacacia, and... the Mimosa Tree, Albizia julibrissin. The latter is native to parts of Asia, but is commonly planted in the U.S. and does well in southern Ohio. While I couldn't find a record of Mimosa Tree as a host for Black Witch, they are documented from another species of Albizia, A. lebbeck.

I asked Omar if any of these trees occurred in the vicinity of his house. His reply: "...we do have a rather large Mimosa tree in our front yard (the photos were taken on my front porch)". Hmmm... One does have to wonder if a gravid female Black Witch dumped her eggs on this Mimosa Tree, and at least one of those eggs made it through the caterpillar and cocoon stage, and thus led to the newly emerged Black Witch on Omar's porch.

Thanks to Omar for finding and documenting a spectacular record, and also for sharing his photos with us.


rebecca said...

Wow. I would love to see one of these. As always when I hear of creatures turning up north of their typical range, though, this story makes me think of climate change and whether it could be a factor here.

Jim McCormac said...

I hope you get to see one someday, Rebecca- they are spectacular! I think warming temperatures surely plays a role in northward advances of highly mobile insects. Among numerous other examples, we had our largest invasion of the southern Little Sulphur butterfly ever (I've written about them on the blog).

Lilac Haven said...

Need to take a close look at our mimosa this evening. ;-)

Sharkbytes said...

Wow- never heard of that one.

Steve said...

Great Job Omar!