This week in the woods, we try to follow the chaotic, speedy flights of sulphur butterflies over fields and along woodland edges. Difficult to chase down, highly variable, and often nearly indistinguishable from one another, the clouded sulphur and orange sulphur both fly at this time of year, possibly in their second or third brood, and may linger as late as November before moving southward. These species in the genus Colias sometimes hybridize with one another and have yellow, orange, or (sometimes in females) white wings and upper sides with black borders – usually solid in males, often with pale spots in females. Their brief courtship displays involve a cruising male finding a female, hitting his wings against her to release pheromones, and joining with her in a twisting skyward ascent.
Dragonflies show a more disciplined, controlled flight than these butterflies and can move each of their four wings independently to perform a variety of aerial feats; they can fly upside down, backwards, and sideways; stop and hover; and change directions on a dime. A syncopated wingbeat rhythm creates turbulence that enables speeds above 30 miles per hour. All these capabilities make dragonflies magnificent hunters on the wing; researchers estimate that they succeed in 95 percent of their attempts to catch prey. They scan for mosquitoes and flies either in flight or, like this female widow skimmer, from a perched position until they spot their victims and can take off to intercept it. While they seem at rest, they constantly scan the sky with their gigantic compound eyes, so sizable that they touch atop their head. Their 30,000 simple eyes (ommatidia) each serve as individual light-and-motion detectors and provide information like that of digital image pixels; about 80 percent of dragonfly brain power is dedicated to processing visual information.
Speaking of eyes, at peak now are the fruiting bodies of eyelash cup fungi (photo by Ann Little). These orange and red fungi develop in clusters on rotting wood. Their “eyelashes,” or hyphal hairs, ring their cupped edges and may help absorb moisture.
What have you noticed in the woods this week? Submit a recent photo for possible inclusion in our monthly online Reader Photo Gallery.