If you’ve walked in New England woods recently, chances are great that you’ve noticed light tan moths with a one-inch wing span flitting about — an odd sight for this late in the year. These are male Bruce Spanworm Moths (Operophtera bruceata), also called Winter Moths, as the adults are active from October to December. They belong to the Geometer family of moths, the second largest family of moths in North America, which includes many agricultural and forest pests. The males are seeking wingless, and therefore flightless, females to mate with. Eggs are laid in the fall, hatch in the spring, the larvae pupate in the summer, and emerge as adult moths in the fall. Bruce Spanworm larvae periodically defoliate hardwood trees, preferring the buds and leaves of sugar maple, American beech and trembling aspen trees.
Of all the insects I’ve found in milkweed patches over the years, the Hummingbird Clearwing is one of my favorites. It is a species of sphinx moth, named for its habit of hovering at flowers while it gathers nectar with its proboscis in a manner similar to that of hummingbirds. In fact, they are often mistaken for hummingbirds. The transparent wings, light brown thorax and dark chestnut abdomen are the field marks to look for. A diurnal moth, the Hummingbird Clearwing can often be found during the day in milkweed patches.
Yesterday’s post was, as you quickly guessed, an eyespot from the forewing of a Luna Moth, Actias luna, one of North America’s giant silkworm moths. With a wingspan up to 4 ½,” it is one of our largest moths. Markings that resemble eyes are found not only on moths, but also on butterflies, birds, fish and reptiles. When they occur on butterflies and moths, eyespots are usually on the wings and are thought to scare off potential predators as well as to direct attacks away from vital body parts. After emerging from their cocoons, Luna Moths live for only about a week, during which time their sole mission is to mate. Like many other ephemeral insects, Luna Moths have no mouthparts and thus, do not eat as adults. (The phenomenal number of Luna Moths this summer may, in part, be due to the mild winter we had, which allowed more pupae to survive.)
The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth (species unknown). Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar. You may be familiar with the common garden pests, cutworms, which are also noctuid larvae. How this larva survives freezing temperatures I do not know, but I have seen several dozen at a time crawling around on top of the snow. Note: Jean Harrison, a fellow nature lover, just identified this larva as Noctua pronuba, a winter cutworm also known as the greater yellow underwing (moth), a recent immigrant from Europe.
If you pull apart a red, fuzzy seed head of Staghorn Sumac (Rhus typhina) this time of year, you will find, in addition to a multitude of seeds, a profusion of scat in the shape of miniscule round, grey balls. If you’re lucky, you’ll find the larval insect that produced this scat. Chances are, according to Charley Eisman, author of Tracks and Sign of Insects, that many of the resident insects are in the Gelechioidea family of moths. The larvae of these moths are consumers of Staghorn Sumac seeds, and judging from the amount of scat usually present, they spend a considerable amount of time inhabiting the seed heads. It’s likely that Black-capped Chickadees and other birds you see gleaning sumac fruit are actually there for the larvae as much as the seeds.
Depending on the woods you walk in these days, you may be greeted by a flurry of inch-long, tan wings belonging to male Bruce Spanworm moths (Operophtera bruceata). From October to December these moths emerge , mate and lay eggs. Females cannot fly; they crawl up the trunk or branch of a tree and send out pheromones to attract winged males. After mating, the female lays eggs which initially are pale green, but become bright orange with age. The eggs hatch in the spring, and the larvae feed on a wide variety of deciduous leaves, favoring trembling aspen, willows, sugar maple and American beech. Periodic outbreaks of these caterpillars can result in heavy defoliation. In 1958 in Alberta, Canada, at the peak of a 10-year infestation, over 50,000 acres were moderately or heavily affected by Bruce Spanworm larvae.
The white-marked tussock moth caterpillar is brightly colored, with tufts of hair-like “setae.” As you might guess, it’s in the same family (Arctiidae) as the woolly bear/Isabella tiger moth. Although these caterpillars are appealing to the eye (of some people), it’s best not touch them, as their hairs break off very easily and can cause a painful reaction on your skin. There are a number of species of tussock moths, many of which, in their larval stage, have these bristles and tufts. As adult moths, most are brown or grey, and live long enough to mate, but they do not eat.
The caterpillar, or larval, stage of a butterfly or moth is the only stage in which the insect has chewing mouth parts. Hence, it is the stage during which a great deal of eating takes place. As the caterpillar eats, it grows larger, and eventually molts its skin, revealing a new, larger skin underneath the old. A cecropia caterpillar molts four times before spinning its cocoon and pupating. The cecropia caterpillar in this photograph has just molted its skin, which is attached to the plant just above the caterpillar’s head. If you look closely, you can see where the colored tubercles were. Within an hour of when this photograph was taken, the caterpillar had eaten its skin.
The larval stage of the Cecropia Moth ( Hyalophora cecropia), a giant silk moth, is a sight to behold. The yellow, blue and red knobs that adorn its 4″ pale green body are striking. Look for this caterpillar on apple, ash, box elder, cherry, lilac , birch, maple and poplar trees, whose leaves it consumes with relish. The larva spins a brown, spindle-shaped, 3” cocoon in the fall, and overwinters as a pupa inside it. In the spring, the adult Cecropia Moth , North America’s largest native moth, emerges. Brown, with a 4” to 5” wingspread, it has no mouthparts, and lives only about a week to ten days, during which time the males mate numerous times, and the females lay eggs. Unfortunately, this species of moth seems to be declining in number, in part because it suffers from parasitism by a fly that was introduced to control the Gypsy Moth.
Crambid snout moths are certainly distinctive, and quite unusual looking. What I thought was the abdomen of this insect turned out to be the head! Crambid snout moths typically rest in this position, with their head down and abdomen and wings up, looking like a bit of bark or twig. When they land on a branch or the trunk of a tree, they are extremely well camouflaged. If you look closely you can see this moth’s long antennae laying against its body, as well as the brush-like appendage in front of its head.