Butterflies in the family Nymphalidae are also referred to as brush-footed butterflies (their front pair of legs are much reduced, brush-like and nonfunctional). Several species of Admiral butterflies belong to this family, and one of the most common in New England is the White Admiral, also known as the Red-spotted Purple. White Admirals overwinter as caterpillars and emerge in late April to feed for several weeks on the young leaves of cherries, willows, poplars and birches, as well as other trees, before forming chrysalises and transforming into butterflies. It is relatively easy to recognize the larva of any species of Admiral butterfly, as they are our only horned bird-dropping mimics. Quite an effective way to discourage predators!
Tiger beetles (named for their ferocity) can be easily recognized by their quick, jerky movements, huge eyes and large, multiple mandibles. Look for these voracious hunters in sunny, open spots where they can easily spot prey and potential predators. The six-spotted tiger beetle is hard to miss, thanks to its iridescent green outer wings, or elytra. Contrary to that which its name implies, this species can have five, two or even no white spots. It is most likely to be found on exposed rocks, logs and tree trunks, whereas the twelve-spotted (may have 12 or fewer spots) tiger beetle tends to prefer moist sandy spots. They both capture and liquefy their prey by masticating it with their formidable mandibles, squeezing it and swallowing the juice. Both of these species of tiger beetles have a two year life cycle, overwintering as adults their first winter, emerging early in the spring, mating and laying eggs during the summer and then overwintering as larvae.
Stoneflies spend the larval stage of their life in streams, but as adults they are terrestrial. When the larvae mature, they leave the streams they grew up in, split their larval skins and emerge as winged adults, ready to mate. Most species mature in warmer months, but there are two families, referred to as winter stoneflies, that emerge at this time of year, perhaps because of the scarcity of predators. You can often find these cold-hardy stoneflies crawling around on top of the snow near streams.
A pileated woodpecker’s diet often shifts with the seasons. One study found that the primary food of these woodpeckers was fruit in fall, carpenter ants in winter, wood-boring beetle larvae in early spring, and a variety of insects in summer. During the winter, with the help of its impressive beak, the woodpecker pries off long slivers of wood from trees containing carpenter ants and exposes the ant galleries. It then uses its long, pointed, barbed tongue and its sticky saliva to catch and extract ants from the ant tunnels inside the tree. This winter diet can be confirmed by examining the contents of a pileated woodpecker’s droppings. Finding these droppings is simply a matter of locating a tree that has a considerable pile of wood chips at the base, indicating that a pileated woodpecker has spent a lot of time working on the tree – long enough to have deposited droppings in and amongst the chips. The droppings crumble easily and reveal a multitude of tiny, black, shiny carpenter ant body parts. (The whitewashed end is due to uric acid.)
The queen is the only wasp in a colony to live through the winter (the others all die), and she usually does so in a sheltered spot such as a rotting log or under the loose bark of a tree (pictured). I wasn’t aware, until discovering this wasp, that queens actually chew a cavity in which to hibernate, but that appears to be the case in some instances. You can see the woody bits of fiber under the wasp that accumulated from her excavating the chamber. The cavity is roughly one inch long and ¼-inch deep. As a rule, hibernating queen wasps protect their wings and antennae by tucking them under their bodies. Some species produce glycerol, which acts as an antifreeze, while others allow ice to form around their cell walls and simply freeze solid. Most queen wasps die over the winter, primarily from predation by other insects and spiders, not the cold. (The pictured wasp had succumbed.) Warm winters are more likely to affect queens, as they emerge from hibernation too soon and starve due to lack of food.
There is no mistaking what bird is responsible for the large holes that a pileated woodpecker makes in an attempt to gain access to the carpenter ants living within a tree. No other bird in North America is capable of excavating holes of this size. Pileated woodpeckers tend to work vertically, and you often find one hole drilled above another. A look inside these holes reveals the galleries that the ants create in order to travel to all parts of their nest located within the dead center of the tree. (Carpenter ants, while omnivorous, do not consume or digest wood; they merely tunnel through it.) A tree’s inner core provides structural support, but is not essential for the tree’s survival. This eastern hemlock’s cambium layer, just inside the bark, is very much alive and the tree may continue to live long after its center becomes hollow.
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.
Meadowhawks are the only small red dragonflies seen in New England (most males are red, most females are brown).The latest species of dragonfly flying in the fall in this area is the Autumn Meadowhawk (Sympetrum vicinum), which doesn’t emerge until mid-summer. It seems a bit incongruous to observe these dragonflies not only flying, but mating and laying eggs in late October, but that is exactly when you can expect to see them. Until there have been several hard frosts, these winged masters of the air are able to keep active by basking in the sun and warming their flight muscles. The two pictured Autumn Meadowhawks are copulating in the typical “mating wheel” fashion, with the male grasping the female behind her head while the female places the tip of her abdomen at the spot on his abdomen (the seminal vesicle) where he stores his sperm. The female Autumn Meadowhawk lays her eggs in tandem with the male (his presence prevents other male meadowhawks from replacing his sperm with their own).
We tend to associate snow fleas, a type of springtail, with winter, as that is when we can easily see their tiny black bodies against the white snow. However, these insects don’t magically appear when it snows – they are in the leaf litter and soil all year round. Snow fleas are considered to be one of the most numerous land animals on earth, with several hundred thousand inhabiting a cubic yard. Even so, it was with amazement that I found several piles of snow fleas at the base of my garage door this morning – it’s the wrong time of year, and most of the individual snow fleas were not scattered apart from each other. Several solid black patches of snow fleas, one patch measuring roughly 6” by 2 ½ ”, piled 1/8” high, had appeared overnight. Something about the warm, humid air this morning may have caused them to leave the safety of the forest floor and for some unknown reason gather in piles on the cement. Once the garage door was raised, the piles disappeared within five minutes, as each tiny snow flea catapulted itself several inches away and disappeared into fallen leaves.
What happens to insects this time of year? A few remain active, such as snow fleas, and some, like monarch butterflies, migrate, but the vast majority of insects overwinter in New England. The insects that stay here are susceptible to freezing due to the fact that they cannot control the temperature of their body. Some insects, such as woolly bear caterpillars, can tolerate having ice form in their tissues, but most insects go into a state known as diapause. When the days start getting shorter, these insects reduce the water content of their body, as water freezes at a high temperature compared to other liquids, and replace it with glycerol, which acts like antifreeze, protecting them from freezing. (Please excuse duplicate post. I’m testing new posting process.)
What happens to insects this time of year? A few remain active, such as snow fleas, and some, like monarch butterflies, migrate, but the vast majority of insects overwinter in New England. The insects that stay here are susceptible to freezing due to the fact that they cannot control the temperature of their body. Some insects, such as woolly bear caterpillars, can tolerate having ice form in their tissues, but most insects go into a state known as diapause. When the days start getting shorter, these insects reduce the water content of their body, as water freezes at a high temperature compared to other liquids, and replace it with glycerol, which acts like antifreeze, protecting them from freezing. (Due to technical problems which hopefully will be resolved soon, I am unable to include a photograph with this post. My sincere apologies.)
Sawflies are often mistaken for wasps, but there are subtle differences in appearance, including the thick “waist” of a sawfly compared to the threadlike waist of a wasp. Their common name comes from the females’ sawlike ovipositor which they use to cut into plants and lay their eggs. Certain species of sawflies overwinter as pupae inside cocoons that they attach lengthwise to twigs. These cocoons are fairly small (the pictured cocoon is just over ¼” long). Sawfly cocoons persist even after the adults emerge in the spring, as they are made of very tough material. Look for capped cocoons during late fall and winter, and empty cocoons, sometimes with the cap still attached, the rest of the year.
You could hardly be blamed for not recognizing that this bright yellow-green, half-inch-long, oval creature is the larval stage of a moth! Possessing suction cups rather than prolegs, the Yellow-shouldered Slug (Lithacodes fasciola) glides, rather than crawls, over the leaf it is consuming. Perhaps this is why these caterpillars show a preference for smooth-leaved trees and shrubs such as basswood, beech, cherry, maple and oak (although this particular individual was found on a witch-hazel leaf). The Yellow-shouldered Slug pupates inside a cocoon all winter, and in the spring a small, brown moth emerges.
Camel crickets are named for their humpback appearance. We don’t often see these wingless insects, for they prefer dark, damp habitats such as under stones and logs, where we don’t often look. However, when there are extreme weather conditions, such as excessive rainfall or the extended periods of hot, dry weather which we have experienced this summer, camel crickets are attracted to damp cellars and crawl spaces, giving us an opportunity to admire their impressive legs. Often mistaken for spiders, camel crickets do have long legs, but only six, not eight, of them. Their two hind legs are obviously longer and stronger than the other four, and enable this cricket to jump three feet high, a skill they use for defense against predators. A local blog reader reports that three nights in a row (camel crickets are nocturnal), due to the force of its jump, a camel cricket tripped a small have-a-heart trap set in their cellar for mice. (Thanks to the Choukas for photo op.)
Bumblebees are nothing if not perseverant. Prying Bottle Gentian’s (Gentiana andrewsii) petals open is a monumental task, and one that few insects, other than large species of bumblebees, attempt — much less accomplish. The relationship of bumblebees and Bottle Gentian is an example of a mutualistic association — the bees benefit by having exclusive access to a bountiful and sugary nectar supply, and the plants benefit by attracting “loyal” pollinators that improve the chances for cross pollination.