Luna Moths and their interesting tails

 

The flawless beauty of a freshly emerged male Luna Moth, Actias luna. This one was resting and drying on a small tree seedling in Shawnee State Forest, Scioto County, Ohio, WAY back on April 29, 2011. While there is much to admire regarding the moth's elegant architecture and coloration, it is the tail streamers that often invite comment.

I think much of the long-standing conventional wisdom was that the tails mostly serve as camouflage of sorts, to help a moth perched among plant matter better blend with its surroundings. At least that's what I always thought. The tails undoubtedly do serve that role, too. I've seen Lunas hanging among green leaves on occasion, and the streamers do seem to break up its shape.

But there seems to be a more critical role for the tails...

I photographed this Luna on April 27, 2014 in Fayette County, West Virginia. While it is also a pretty fresh, recently emerged moth, this insect has apparently had a rough row to hoe. The tail streamers are nearly gone, and a big chunk is missing from the wing on the left.

Recent research has convincingly demonstrated that the tails present a false flag to hunting bats. The fluttering streamers when the moth is in flight creates an acoustic signal that dominates an approaching bat’s echolocation sonar. It fixates on the tails and, more often than not, ends up clutching a piece of tail while missing the body. The moth escapes, still with an opportunity to reproduce. Laboratory experiments featuring normally tailed moths and Lunas that had their tails removed, and a Big Brown Bat (Eptesicus fuscus) showed that the bat caught only 35% of the moths with tails, but its success rate skyrocketed to 81% with the tailless moths.

I am about sure that's what happened to the moth in the photo above - a survivor of a failed bat attack. The V-shaped bite mark on the wing, especially, is the calling card of a bat.

My whole life has been moths for a while, because of a book project, and it has me frequently dipping into the files and dredging up old photographic chestnuts such as these moths. 

Flora-Quest goodies

I spent last weekend in southern Ohio's Shawnee State Forest, helping lead field trips for Flora-Quest. This was the fifth year for this great event, and you can't go wrong by putting in your 2012 calendar. As always, event leaders Cheryl Harner and Paula Harper did a fabulous job with logistics and all aspects of the event. The plants cooperated as well, and all groups saw lots of great stuff. A few highlights follow.

A Blue-headed Vireo expertly crafts its nest, which is woven finer than a Longaberger basket. This vireo nearly always sites its nest at the fork of two spindly branches, far out from the trunk. It would be quite difficult for any tree-climbing predator to reach the nest, such as black rat snakes. This one was in a sugar maple, and 20 or so feet off the ground. Thanks to Chris Bedel, who spotted the nest and tipped us to its location.

Blue-headed Vireos are northerly breeders of cool, often boreal forests, but they seem to be expanding southward. I know of several sites for nesters in Shawnee, although one isn't often so lucky as to stumble into the actual nest.

There must have been an excellent emergence of luna moths, as a number of people found them. I was talking with some birders along a forest road when I glanced up and saw this beauty hanging from a plant. In short order, we found another, mating pair. This lime-green moth is an outstanding twig and leaf mimic. Notice how the purplish bar along the forewings resembles a twig. The rest of the wings look like a green leaf hanging down, and the two tear drops coming off the purple "twig" even look like tree buds.

This luna is a male, as evidenced by the broad, fernlike antennae. He uses them to sense the pheromones released by females, and can detect these chemical lures from a mile or more.

Pink lady's-slippers, Cypripedium acaule, always a crowd pleaser. It seems to be a great year for orchids, as we saw large numbers of many species - far more than in lean years. The sight of dozens of pink lady's-slippers is a spectacle not soon forgotten.

This is a bizarre orchid we were really hoping to show Flora-Quest attendees, and luck was with us. It is whorled pogonia, Isotria verticillata. These scarce oddities apparently don't even surface in some years; rather, they live in the subterranean as rootstock. In good years, whatever causes those, the weird little orchids burst forth and put on a show.

It'd be quite easy to walk right by a whorled pogonia. They only stand perhaps six inches in height, and blend well with the dappled light of the forest floor. Once seen, they encourage prolonged inspection, as the sum of the orchidaceous parts creates an artistically stunning arrangement. Most conspicuous are the long deep purple sepals, spanning outwards like the blades of a windmill. The waxy green leaves form a whorl that caps the thick whitened stem.

The actual flower? Well, it's rather overshadowed by the orchid's other parts, but like every other orchid I have come to know, it is ornately intricate upon close examination.