Although more species of insects are out and about during the warm days of summer, I often see the most interesting ones in the fall. Two appeared in the last couple of weeks — one on the side of my house and the other in my email inbox — that sent me to my references to try to identify them.
The insect on the side of the house appeared just a few days after writing about seeing Carolina mantises, and at first I thought it might be another mantid. I’ve often found Chinese mantises chowing down on katydids and other invertebrate prey there. I found, on closer inspection, that the insect was About two inches long, with a wide body and spindly legs and its head was distinctly not the powerful, triangular head with huge eyes that are typical of mantids. Instead, it was straight and narrow, hardly looking like a head at all. I realized that this was stick insect, but unlike the “northern walking sticks” — the most common species of walking stick (or “walkingstick”) in North America, according to BugGuide.net — that usually show up this time of year.
After searching through my guides and online, I decided, mostly through the process of elimination, that my visitor was a “northern two-striped walkingstick” (Anisomorpha ferruginea). While its southern cousin (Anisomorpha buprestoides), which does not range this far north, can have two vivid white stripes running down the length of its body, the northern species’ stripes are darker and more subtle, almost blending into the rest of the insect’s back, which is rusty-colored. (Its species name, ferruginea, comes from the Latin for “rusty.”)
Not a lot is known about stick insects, but their bizarre appearance has obviously stirred the imagination of humans over the centuries. In the insect order Phasmatodea — from the Greek for “apparition” or “phantom” — walkingsticks’ common names include “evil’s riding horse,” “prairie alligator,” “witch’s horse,” “devil’s darning needle,” “scorpion” and “musk mare,” according to Andrew Nelson Caudell in a 1903 article in the “Proceedings of the United States National Museum.”
Despite the fierce pseudonyms, stick insects tend to live quiet lives dining on leaves of trees and shrubs, unlike the carnivorous mantids that they resemble but which in fact are in a different insect order (Mantodea). The stick insects’ shape, coloring and postures help them blend into the branches of the woody plants on which they feed.
While stick insects dine on leaves rather than animals, some have some pretty nasty defenses. According to an article on southern two-lined walkingsticks in the “Creature Feature” section of the University of Florida’s entomology and nemotology department’s website (entnemdept.ufl.edu), “musk mare” is a “particularly apt” name for species in the Anisomorpha genus, which can squirt “a strong-smelling defensive spray that is painfully irritating to the eyes and mucous membranes” at perceived threats up to 15 inches away.
As with many insects, female southern two-lined walkingsticks are larger than the males and tend to have fatter bodies. Females are about 2.5 inches long, while males measure in at about 1.5 inches. The northern species is distinguished by its smaller size, paler color and lack of conspicuous striping, according to the article. With the walkingstick at my house, the stripes were so subtle that I only noticed them after I enlarged the photos I’d taken. Both the southern and northern species in the genus are commonly found with the small males riding atop the larger females, the article notes. Judging by the size and shape of the one on my wall, I figure was a female.
Although the southern species is “quite abundant” (“several thousand” mating pairs have been reported in the Ocala National Forest), according to the article, they are not known to cause “serious defoliation as has been reported for some other stick insects.” (These would include the northern walking stick, according to other sources.) The article also notes that these stick insects will often congregate under loose bark or in other sheltered places. As I’ve observed here, the adult stick insects are most abundant in the fall, when they breed and lay their eggs. According to BugGuide.net, all but one of North America’s stick insects are wingless (the lone winged one being native to Florida).
Adult stick insects are not the only invertebrates that are more prevalent in the fall. Moth caterpillars are also abundant this time of year. These “cats” are generally furry, with tiger and tussock moths the most common where I live, on a forested mountain. Some moths commonly called “tussock” actually belong to the tiger moth (Arctidae) family, not the tussock moth family (Lymantriidae). As I’ve noted before, most remind me of Yorkshire terriers because of their tufts of hair, usually of mixed hues, that stick out from their bodies.
While I’ve written about and photographed several species of these cats, a photo of one new to me, Euchaetes egle showed up in my email inbox recently, sent by Rappahannock resident Ann Callaway. As with the monarch butterfly, the host plant of this moth is milkweed, hence the species’ common name, “milkweed tussock moth.” I’m not surprised that I haven’t run into this particular tussock-moth larva, since I live in a forest, with only a few milkweed plants growing along the edges and in my herb garden.
Euchaetes egle belongs to the Arctidae family and, as with many moths, the adult form looks less impressive than its young. The larva has longish hair, mostly tiger-striped, along the body and fringes of black and white hair sticking out. The adult moths have brown wings but do retain the bright tiger-like stripes of the caterpillar on their bodies.
As I’m writing this, in the third week of October, fall weather has really set it, with temps hovering around 60 degrees. In taking a short walk this afternoon, I saw several other hardy insects still out and about, including comma butterflies looking for food in the compost pile, a few species of dragonfly patrolling for prey, and several moths fluttering around with no immediate apparent goal but to warm up.
© 2014 Pam Owen