White Admiral/Red-spotted Purple Caterpillars Emerge from Hibernation
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!
Six- and Twelve-spotted Tiger Beetles Active
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.
Eastern Commas Flying
Commas are a group of butterflies also known as anglewings (for obvious reasons). There are several species of commas in New England, all of which have a silver mark in the shape of a comma underneath each hind wing. Like mourning cloaks, these butterflies overwinter as adults in bark crevices, logs or other protected spots. You often see them in the woods, where they feed on tree sap, mud, scat and decaying organic matter. When perched with their wings closed, they are extremely well camouflaged and easily mistaken for a dead leaf.
Mourning Cloak Butterflies Emerging from Hibernation
A male mourning cloak butterfly basks in the sun on an eastern hemlock while its dark wings act as solar collectors, warming the hemolymph (a circulatory fluid analogous to blood) in the wing veins and returning the warmed fluid to the butterfly’s body until it reaches a temperature sufficient for flight. This butterfly has just emerged from hibernating in a sheltered spot, such as behind loose bark. Because they overwinter as adults, mourning cloaks are one of the first butterflies to be seen in the spring. The adults mate and lay eggs, and the caterpillars that hatch from the eggs will metamorphose into adults in June or July. After feeding for a short time, the adults become dormant (estivate) until fall, when they re-emerge to feed and store energy for hibernation.
Goldenrod Ball Gall Fly Larva
The round “ball” that is often present on the stem of goldenrod plants contains the overwintering larva of a fly (Eurosta solidaginis). A year ago an adult female fly laid an egg in the stem of the goldenrod plant. The egg hatched and the larva proceeded to eat the interior of the stem. As it did so, the larva excreted chemicals which caused the plant to grow abnormally, creating a ball-shaped “gall.” If you were to open a goldenrod ball gall today, you would probably find an overwintering larva (if a downy woodpecker or parasitic wasp hadn’t gotten there before you). Within the next few weeks the larva will pupate, and as early as April the adult fly will emerge from the gall, having crawled out the passageway that it chewed last fall. An inflatable “balloon” on its forehead allows the fly to burst through the remaining outermost layer of tissue at the end of the passageway. The adult fly lives about two weeks, just long enough to mate and begin the process all over again.
Mating Flies
It’s hard to believe that flies are not only active but mating now, given the snow and low temperatures that Vermont is still experiencing, but these two flies were perched atop coyote scat doing just that. They are in the Heleomyzidae family, whose members are often found in dark or cold places, and are most likely to be encountered in the spring or late fall. There are species associated with caves, mammal burrows, carrion and birds’ nests, in addition to scat.
Snow Spider
It’s always surprising to find any form of life crawling on top of the snow, but for some reason spiders seem particularly fragile and susceptible to the elements. There are species, however, that remain active in winter, even in the northeast. Most live in the leaf litter beneath the snow, but they often emerge when temperatures are about 25°F to 35°F. Tentative I.D. has the spider in the photograph belonging to the genus Tetragnatha.
Winter Stoneflies Emerging and Mating
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.
Hibernating Queen Wasps
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.
Blueberry Stem Gall
If you happen to notice a ¾” to 1 ¼”- long, brown kidney-bean-shaped or round structure on a blueberry bush this time of year, you’ve come upon the blueberry stem gall – a summer and winter home for a dozen or so wasp larvae that will pupate and emerge in the spring as very small (less than 1/8”) black wasps (Hemadas nubilipennis). Last summer a female wasp laid her eggs in a tender, developing blueberry shoot. She then climbed to the tip of the shoot and stabbed it repeatedly, causing considerable damage. Within two weeks the eggs hatched, and the larvae began feeding, which, along with the egg-laying, stimulated the formation of the gall. Initially a blueberry stem gall is green and spongy; by fall it turns red, and by late autumn, it is brown and woody. Next summer, look for multiple holes in these galls that were chewed by the exiting wasps.
Spider Egg Sac
As a result of many years of evolution, spiders have developed the use of different silks produced by seven glands for various functions (ballooning, webs, wrapping prey, dragline, egg sac, etc.). The tubuliform gland is responsible for the large diameter silk fibers used in the construction of egg cases. Unlike other silk glands, which synthesize protein throughout a spider’s lifetime, the tubuliform gland synthesizes silk for only a short time in a spider’s life, just before eggs are laid. This silk is synthesized only by female spiders, and is the stiffest type of silk, which makes it a very protective covering for eggs. The pictured overwintering spider eggs had three layers of protection: bark (the photo is of the underside of a piece of loose bark), an outer silk cocoon covering the egg sac and the egg sac itself – a tough layer of silk covering the eggs. (Reluctantly I opened the sac for the sake of an educational photograph, and did my best to re-wrap the eggs.)
A Great Christmas Present!
If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill. A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!
One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”
In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”
I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!
Bruce Spanworm Moths Flying
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.
Cecropia Moth Cocoon
This past summer there seemed to be more giant silkmoths than usual, including Cecropia Moths (Hylaphora cecropia). (see http://naturallycuriouswithmaryholland.wordpress.com/2012/06/04/cecropia-moth-2/ ). Assuming many of these moths bred and laid eggs, and that most of the larvae survived, there are probably a large number of Cecropia cocoons in our woods. Even so, it is not an easy task to find them, as they are so well camouflaged, and are often mistaken for a dead leaf. Cecropia caterpillars spin silk and fashion it into a three-inch long, tan cocoon (giant silkmoths make the largest cocoons in North America) which they attach lengthwise to a branch or stem. There is a tough but thin layer of silk on the outside, which protects an inner, thicker and softer layer of silk on the inside. The caterpillar enters the cocoon through loose valves it makes in both layers, which are located at the tip of the cocoon’s pointed end. Shortly after the larva crawls inside both of these layers, it pupates. Its skin splits, revealing a dark brown pupa. For the rest of the winter and most of the spring, it remains a pupa. In early summer it metamorphoses into an adult moth and exits the cocoon through the same valves through which it entered.
Wasps Still Flying
The lingering warm weather and the few remaining flowers (such as the mustard in the photograph) have allowed worker wasps to extend their lives this fall longer than many years, for once several hard frosts hit, they will die. Unlike honeybees, the queen of social wasp colonies lives only about a year, but that is longer than the workers. In the late summer the (old) queen stops laying eggs and the colony soon begins to decline. In the fall, mated female offspring of the queen seek overwintering sites such as rotting logs. In these protected spots they tuck their wings and antennae under their bodies, and hunker down for the winter. The remainder of the colony does not survive the winter. If predators such as spiders don’t kill the new queens, and if they don’t emerge early due to a warm winter and starve due to lack of food, the young queens begin building nests and laying eggs in the spring.
Autumn Meadowhawks Mating
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).
Piles of Snow Fleas
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.
Insects in Winter
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.)
Insects in Winter
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.)
Woolly Bears on the Move
Although it’s fun to try to predict the severity of the coming winter by the amount of brown on a woolly bear caterpillar (the more brown = the milder the coming winter, according to folklore), the coloration of any given woolly bear caterpillar has more to do with its diet and age than the coming weather. The more a Woolly Bear eats, the more frequently it molts, and each time it molts a portion of the black hairs (setae) is replaced by brown ones. A Woolly Bear can molt up to six times — the best fed and oldest woolly bears, which have molted the most number of times, have the widest brown bands. (After overwintering as caterpillars, Woolly Bears pupate and emerge as small, brown moths called Isabella Tiger Moths, Pyrrharctia isabella.)
Sawfly Cocoon
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.
Jumping Spiders
Jumping spiders are aptly named as they can spring more than 50 times their own body length to land on unsuspecting prey. They hunt actively rather than catching prey in a web and they have excellent vision, with four big eyes in front and four smaller eyes on the top of their head. Jumping spiders have three-dimensional vision which allows them to estimate the range, direction and nature of potential prey, essential skills for a predator that catches prey by pouncing on it.
Yellow-shouldered Slug Moth
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.
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