Wednesday, September 26, 2012

Meet the Cycnias

Spreading Dogbane, Apocynum androsaemifolium, easily the handsomest of the three dogbanes that occur in Ohio. It's rather local, but widespread, and prefers damp partially shaded sites.

The flowers of Spreading Dogbane are magnificent, at least by dogbane standards. The large whitish corollas are prominently striped with pink, with a prominent outward flare to the corolla lobes.

As with the other dogbanes - and their close allies the milkweeds - Spreading Dogbane has thick milky latex coursing through its veins. Tear a leaf and you'll spark a gusher of the stuff. This latex is fairly nasty, as it is rich in toxic cardiac glycosides. The goo is an effective anti-herbivore defense, and dogbane's chemical arsenal safeguards it from most leaf-noshing caterpillars.

Photo: Alison Hunter/Wiki Commons

But not all herbivores are repelled by dogbane toxins. If you ever encounter a pale brown caterpillar that looks like an escapee from a box of pipecleaners, and it's snacking on dogbane, it's apt to be the larva of the Delicate Cycnia (Sik-nee-ah), Cycnia tenera. The caterpillars of this moth are among the few species of Lepidoptera that have successfully battled through the plants' chemical protection.

If the fuzzy caterpillars survive the threat of tachinid flies and other parasitoid predators, this is what they'll become - one of our most elegant moths. Delicate Cycnias are easily recognized by their flawless creamy-white complexion, disrupted only by a showy orange-yellow band that gilds the forewings and head.

The Delicate Cycnia seems to be pretty common and widespread in Ohio, and if you keep a watch, you're likely to encounter one.

Butterfly-weed, Asclepias tuberosa, fabled among butterfly connoisseurs for its magical ability to lure the fluttery crowd to its rich nectar. Sometimes butterflies get so punch-drunk on butterfly-weed that you can practically handle them as the insects plumb the depths of the orange blossoms.

It's not only butterflies that depend on this showy milkweed. Look carefully, and you might spot an interesting caterpillar in this shot.

We zoom in, and unmask the tubular orange beast. This is the larva of a MUCH rarer moth than the aforementioned Delicate Cycnia. What we have here is the caterpillar of the Unexpected Cycnia, Cycnia inopinatus, which is an Ohio endangered species. I photographed this cat last July in Adams County, which is one of only two Ohio regions where it is known to occur.

Unexpected Cycnia caterpillars are clad in an incredible shade of soft orange that matches the flower color of Butterfly-weed to a remarkable degree. They'll eat other species of milkweed, and probably even dogbane, but seem most at home on the Butterfly-weed. I was delighted to have the opportunity to see this caterpillar, one of several that we found in a small prairie. It wasn't entirely unexpected, though, as I was with John Howard and he knew that they could be found in this spot.

I've never seen an adult Unexpected Cycnia, but this is what they look like. Work took me to the OSU Museum of Biological Diversity today, and Dave "Mothman" Horn was kind enough to pull out a specimen so that I might photograph it. Note how the orangish forewing gilding only extends to the midwing, and this species is a bit less robust than the similar Delicate Cycnia. The label for this specimen is partially visible, and records the collection locale as the Oak Openings near Toledo. This interesting and imperiled ecosystem harbors the greatest concentration of rare flora and fauna in Ohio. Its close runner up for rarity treasure trove is the prairies of Adams County - the other Ohio region in which the Unexpected Cycnia occurs.

There are two other Cycnia species. One, the Collared Cycnia, Cycnia collaris, is a westerner that doesn't make it as far east as Ohio. The fourth species is the Oregon Cycnia, C. oregonensis, and despite its distinctly occidental name, it does occur sparingly in Ohio. I've seen it once - I think - also in Adams County. Those photos are on another drive, or I'd slap one up.

Mothing is a fascinating pursuit, and Ohio moth'ers should be in for a few treats next year. A new publication on Buckeye State moths is in the works, and a scheme is afoot to hold what should be a real "Mothapalooza".


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5 comments:

Pat Ernst said...

Very cool, Jim. Lately I've started to pay more attention to moths, so I really enjoyed your article.

Jim McCormac said...

Thank you, Pat!

Sharkbytes said...

Very cool! I got some nice pix of spreading dogbane this summer, and then forgot. I should use them on my blog.

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Anonymous said...

Thanks for sharing the photos of the Delicate cycnia. I do enjoy the village of insects that rely on the milkweed plants. There are a few species of milkweed plants in my home gardens. I find Monarch eggs and caterpillars on Asclepias incarnata and A. syriaca plants but not on the A. tuberosa plants. Although the adults do enjoy the nectar. Why do you think they do not prefer Butterfly weed as a host plant?