Orchids and Moth Eyeballs

 

These are the leaves of one of our more interesting - and overlooked - orchids, the Cranefly Orchid (Tipularia discolor). It, along with the Puttyroot Orchid (Aplectrum hyemale), sends its photosynthetic leaves up well after flowering, and they photosynthesize over winter, withering away before the following summer's flowering period rolls around. It's generally far easier to detect the plants by their leaves on the barren leaf litter of late fall and winter, than the spindly flowering stalks in the shady understory of July/August.

The flowering spike of a Cranefly Orchid, imaged on August 3, 2023. I purposely chose a more open backdrop to better showcase the flowers. When in dense forest understory with dappled light filtering through the canopy, it's much harder to see the plants.

Close up with the strange, spindly flowers of Cranefly Orchid, each with its long nectar spur. In order to access the nectar reward, a pollinating moth must insert its elongate proboscis down to the bottom of the long tubes to reap a nectariferous reward. In the process, its fuzzy eyeballs are likely to come into contact with the reproductive flower parts. That includes the specialized structures known as pollinia, which are little bag-like bundles of pollen.

Moths of a handful of species are the only known pollinators of Cranefly Orchid, and it was an Ohio botanist, Warren Stoutamire of the University of Akron, who first published on this phenomenon. Stoutamire was tipped to a Cranefly colony by an orchidologist friend who had observed visiting moths, went to the site and documented five species of moths visiting the flowers. He reported a faint but evident citrus-like aroma that was exuded by the flowers - a moth lure, no doubt. The bizarre, asymmetrical arrangement of the flower petals likely serve to guide visiting moths to the optimum floral targets, the pollinia, and the stigma.

Jump to last Saturday night and the now legendary event known as Mothapalooza. We just celebrated our 12th event last weekend. About 135 attendees came, from many states, some of them as distant as California, New Hampshire, and Texas. Nocturnal mothing is a big part of Mothapalooza, and this year there were perhaps a dozen light stations in scattered locales, all in rich mostly forested habitats of Highland and Pike counties. Most of them were located in the fabulous 3,000-acre Arc of Appalachia preserve known as the Highlands Nature Sanctuary. The Arc now runs Mothapalooza and does an excellent job with it.

The moth above is called the Zebra Conchylodes (Conchylodes ovulalis) and it is a beauty. It even made the cover of THIS RECENT BOOK on moths. Norah Tempus and her exceptionally sharp 16-year-old eyes noticed a strange anomaly on the moth's left eyeball - look closely, and you'll see it. She started showing a photo around, wondering what the yellowish blob might be. After some speculation, someone hit on the idea of orchid pollinia. I recalled Warren Stoutamire's work with Cranefly Orchid and suggested that it might be pollinia from that species. Problem is, none of us knew exactly what said pollinia looked like.

It was time for me to pull out the bizarre but effective Canon MP-E 65mm mega macro lens. It's like shooting through a microscope and can drill down on tiny details. To use it well requires twin-lite flashes mounted on the front of the lens, and a tripod for maximum stabilization. This moth was perched on the side of a building and only a foot or so above ground level. So, I used a micro tripod, and a two-second timer delay so I wasn't even touching the camera when it fired. Settings were f/16, ISO 200, and 1/200 second (the camera's sync speed). While I had to crop the resulting image somewhat, it would have had to have been cropped FAR more if I had used my 100mm macro lens. The result would have been a pixelated blob, with details hard to decipher. See CAMERA NOTES at the end of this post for details on the MP-E 65 lens.

But now we can clearly see the tiny yellowish pollen sacs, which sit atop a white tube-like structure known as a viscidium. The viscidium is sticky, like Elmer's Glue, and when the pollinating moth's eye comes into contact with it, the viscidium affixes itself to the insect. When the moth pulls away, the pollen sacs come with it, and hopefully (for the orchids) are transported to another Cranefly and deposited onto the new plant's stigma, thus pollinating it.

We quickly set about researching Cranefly Orchid pollinia and found several images that appear to be the spitting image of the pollinia in my images. Cranefly is also pretty common in the adjacent forests, although I would bet that the moths have a much easier time finding flowering specimens than we do.

PHOTO NOTES:

Photo: Wikipedia

Canon released the MP-E 65mm f/2.8 macro lens in 1999, and unfortunately for macro enthusiasts, the lens was discontinued in 2023. I got mine in 2013 or thereabouts, and probably will never sell it - especially now that it's no longer made. I probably only break it out a few times a year, but when I do it certainly comes in handy, such as for the orchid pollinia in this post. The MP is incredibly useful for tiny things and can go far smaller than the what the superb Canon 100mm f/2.8L macro lens can handle. Taking an image through it generally is not a quick point and shoot experience, though. It really should be tripod-mounted, and twin-lite flashes (I use Canon's MT-24EX unit) are pretty much a necessity. The two small flashes are controlled by a commander on the camera's hot shoe, and the flashes can be rotated to cast light directly in front of the lens.

The lens stops down to f/16, and that's usually where I set the aperture for maximum depth of field. Focus definitely takes tweaking. There is no auto focus, and to attain focus requires twisting the lens barrel which then telescopes the lens in and out. The further out you go, the closer it focuses. With no auxiliary light, at small apertures, the photographer can't see through it - there isn't enough light entering the tiny front lens. Twin-lites have pre-flash lights that can be triggered by a half tap of the shutter button. The pre-lights emit enough of a glow that subjects can be found and focused on. Otherwise, the operator would have to use a flashlight or some other auxiliary light source. Once all is good and I think that I've got a decently sharp focus on my target, I press the shutter button and wait. Wait, because it's highly advisable to use either the 2-second or 10-second timer delay mode. That way, there will be no residual movement of the camera/tripod caused by deploying the shutter button. A remote shutter release cord would also work. It also helps to have a non-moving subject. Moving targets, as long as they're pretty slow, are possible to shoot but far more challenging.