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Metamorphosis

Caterpillars Molting

6-25-14 caterpillar molting 044A caterpillar is the larval stage of a moth or butterfly. It is the only stage that has chewing mouthparts, and therefore a caterpillar spends most of its waking hours eating. This consumption of food results in massive growth, making its skin/exoskeleton very tight. When this happens, a hormone called ecdysone is produced, prompting the caterpillar to molt, losing its old exoskeleton (to left of caterpillar in photo) under which is a new and larger exoskeleton. After the molt, while the new exoskeleton is still soft, the caterpillar swallows a lot of air, which expands its body. Then, when the exoskeleton hardens, it lets the air out and has room for growth. Caterpillars molt four or five times as they grow. Each different caterpillar stage is called an instar. (Photo: Forest Tent Caterpillar)

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Eastern Tent Caterpillars Hatching & Building Tents

eastern tent cat. FINAL 090The adult Eastern Tent Caterpillar moth lays her eggs in late spring or early summer on a tree whose leaves its larvae will eat (black cherry and apple trees are favorites). Two to three hundred eggs are deposited in a mass that encircles a thin branch. Within three weeks fully formed caterpillars develop inside the eggs. The caterpillars remain there until the following spring, when they chew their way out of the eggs just as the buds of the host tree are starting to open. As soon as the caterpillars emerge, they construct a silk tent within which they reside, enlarging it as they grow in size.

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Promethea Moth Cocoon

4-22-14  promethea cocoon 478When a Promethea Moth caterpillar, one of our giant silk moths, is ready to pupate at the end of the summer, it strengthens the stem, or petiole, of a leaf on its host plant with silk and then attaches the silk to a nearby branch, assuring that the leaf will remain attached to the tree. (Imagine having the instinctive foresight in your youth that this caterpillar had!) The caterpillar then curls the leaf around itself and spins its cocoon inside the curled leaf. The cocoon dangles from the host plant throughout the winter and in early summer the moth emerges. Now is the perfect time for finding a Promethea Moth cocoon, as last year’s leaves are gone on most trees, and this year’s buds have yet to open. Look for a tree or shrub that has just one dead leaf hanging from one of its branches. (Cecropia caterpillars favor black cherry, poplar, ash, maple, oak and willows trees among others.)

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Cecropia Moths Pupating

11-11-13 cecropia cocoon dissected  056Our largest North American native moth, the Cecropia Moth, Hyalophora cecropia, spends the winter as a pupa inside a cleverly-crafted 3” – 4”-long shelter, or cocoon, which it creates and attaches lengthwise to a branch while still in its larval stage. The Cecropia caterpillar, with the silk glands located near its mouthparts, spins not one, but two silk cases, one inside the other. In between the two cases, it spins many loose strands of very soft silk, presumably to enhance the insulating properties of the cocoon. Inside the inner case, the caterpillar splits its skin and transforms into a pupa. Come spring, an adult moth will emerge from the pupal case and exit the cocoon through one end which was intentionally spun more loosely, allowing the moth to crawl out the somewhat flexible tip. (Note: dissected cocoon was not viable.)

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Bruce Spanworms Emerging & Mating

11-7-13 winter moth IMG_4880I try not to repeat post topics, but in the past two days the sudden emergence of inch-long, tan moths in the woods has been so dramatic that I couldn’t not mention them. These ghost-like, light tan moths are referred to by entomologists as Bruce Spanworm moths, Operophtera bruceata, named after an entomologist by the name of Mr. Bruce. They are often called Winter Moths, due to the fact that they are one of the latest moths to be seen flying, as well as Hunter Moths, as they share the woods with hunters at this time of year. From October to December Bruce Spanworm moths emerge, mate and lay eggs. While this timing is unusual, it makes sense when you think about it — many birds, their primary predators, have left for their wintering grounds. All the moths you see in the air are males — females are wingless and cannot fly. The females crawl up the trunk or branch of a tree and send out pheromones to attract winged males. After mating, the female lays eggs which hatch in the spring, and the larvae feed on a wide variety of deciduous leaves, favoring Trembling Aspens, Sugar Maples, American Beeches and willows. Periodic outbreaks of these caterpillars can result in heavy defoliation.

NB: “This is easily confused with Operophtera brumata – Winter Moth, which is an introduced species from Europe and an abundant pest in the Northeast. Also easily confused with Autumnal Moth (Epirrita autumnata).” Kent McFarland


Ribbed Pine Borer’s Winter Pupal Chamber

11-6-13  ribbed pine borer winter shelter 132The larva of the Ribbed Pine Borer, Rhagium inquisitor, (a beetle) lives just under the inside of a pine tree’s bark. It is a long-horned beetle, and in the fall, when it’s ready to pupate, it creates an oval cell by chewing a relatively flat chamber approximately 1 ¼” long. The Ribbed Pine Borer uses the woody fibers it chewed to form a raised “wall” surrounding the chamber. It then pupates inside the wall, and overwinters in the chamber as an adult beetle, emerging to mate in the spring. (Thanks to Kitty Stanley for photo op.)

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Green Lacewing Larvae Use Corpses as Camouflage

9-19-13 lacewing larva  232Green lacewings are aptly named for the prominent venation of the adults’ wings. Some species in this insect family even have “ears” in the larger veins that allow them to detect the ultrasonic sounds made by hunting bats. Lacewing larvae and adults are both predators of soft-bodied insects such as aphids. Larval lacewings have long, hollow mandibles with which they puncture prey and suck out the liquefied contents, leaving the woolly husks. Some species of lacewing larvae have hairy backs, and camouflage themselves when in the presence of woolly aphids by sticking aphid husks on these hairs. These “trash packets” camouflage the lacewing larvae from predators, including ants that would otherwise attack the larvae if they recognized that they were lacewings and not woolly aphids.

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American Elderberry & the Elderberry Borer

9-9-13 American elderberry 183Interestingly, while the ripe fruit of American Elderberry (Sambucus canadensis) is used in the production of wine, pies and jelly, the leaves, stems, roots and unripe fruits of this plant are poisonous, due to the presence of calcium oxalate crystals. Elderberry Borers (Desmocerus palliates) seem immune to these crystals, however. They lay their eggs at the base of the plant, and the hatching larvae then burrow their way into the stems and eat tunnels into the roots of the plant. Adult beetles that emerge and are present through the summer are hard to miss, with their shimmering blue and yellow/orange outer wings, or elytra.

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Young Pickerel Frogs Underfoot

9-6-13 young pickerel frog 049If you remember visiting a pond last April or May and hearing a low, snoring sound (the mating call of the male Pickerel Frog) you might see the end results of those snores if you re-visit the pond now. Young Pickerel Frogs the size of quarters are currently abundant on the banks of the ponds in which they grew up, as well as in nearby vegetation. After emerging from the water sometime between July and September, many of these first year frogs move into nearby fields, meadows and damp woods. They are only a few weeks away from burying themselves in mud at the bottom of the pond, where they will hibernate all winter.

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Black Swallowtail Larvae Soon to Form Chrysalises

8-29-13 black swallowtail larva and QALace 028In its younger days, this Black Swallowtail larva resembled a bird dropping, but in successive molts a green (or white), yellow and black pattern develops. Often discovered in vegetable gardens on carrot, parsley and dill plants, it also feeds on wild members of the carrot/parsley family (Apiaceae), including its favorite, Queen Anne’s Lace (pictured). Seeds as well as leaves are rapidly consumed, as the time for one last molt and the development of a chrysalis in which to overwinter approaches.

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Young Spring Peepers Now The Size Of Your Baby Fingernail

8-28-13  spring peeper & Jap. beetle 066It takes roughly two months for Spring Peeper tadpoles to metamorphose into adults, and unlike other frogs, they don’t complete this process in the water. Young Spring Peepers leave their ponds at an earlier stage of development than most frogs – they have four legs and lungs when they come out of the water, but most of them also still have a tail which is absorbed shortly after they become land dwellers. Adult Spring Peepers measure roughly ¾” (males) to 1 ½” (females) in length. As you can see in this photograph, this fully metamorphosed young Spring Peeper is hardly bigger than a Japanese Beetle, and it has completely lost its tail, so it was even smaller when it hopped out of the water!

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Toadlets Dispersing

7-17-13 toadlet 021The American Toad tadpoles that hatch in May and June begin to transform into toadlets after about three weeks. Metamorphosis is a complex series of changes both external and internal. Lungs are formed, gills are absorbed, the digestive system changes from a primarily vegetarian one to a carnivorous one, legs appear and the tail is absorbed. When these changes have taken place, the toadlets leave the water but tend to linger near the pond for days or weeks. Eventually they disperse, and by July you start finding small toads in the woods and around your lawn and gardens.


Adult Stoneflies Emerging

7-2-13 stonefly adult 058Stoneflies spend their larval stage on the bottom of streams, in amongst the stones for which they’re named. Some species of larval stoneflies feed on decomposing organic matter, others are predators. As adults, very few stonefly species feed due to their short life span. Those that do feed on algae and lichens, nectar, or pollen. After shedding their skin 10 to 22 times (depending on the species), the larvae crawl out of the water, split their skin a final time and emerge as winged adults. Most emerge in the spring or early summer, though some species mature in the fall, and even in winter. Most larvae spend 10 to 11 months under water, and only 1 to 4 weeks as terrestrial adults. The adults spend their days hiding on the branches or leaves of streamside vegetation, and crawl around at night. They usually only fly to disperse to a new habitat, which is surprising, given the size of their wings.


Eastern Commas Flying

4-23-13 green comma IMG_9353Commas 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

4-11-13 mourning cloak IMG_2827

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

3-22-13 goldenrod ball gall fly larva IMG_6182The 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.


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!


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.

 


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.)


Goldenrod Spindle Gall

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There are three fairly well-known galls (abnormal plant growths caused by a variety of organisms) on goldenrod – the goldenrod ball gall (round swelling in stem caused by a gall fly), the goldenrod bunch gall (leaves at top of plant are bunched up into a mass caused by a gall midge) and the goldenrod spindle gall (elliptical stem swelling caused by a moth).  The amazing thing about insect galls is that not only do they provide shelter for the insect, but they are nutritious and serve as the insect’s food supply as well.    The spindle-shaped galls are home to the larval stage of the goldenrod gall moth (Gnorimoschema gallaesolidaginis).  In the late fall the adult female moth lays an egg on a low goldenrod leaf, where it overwinters. The larva, or caterpillar, hatches out the following spring and makes its way from the now dead leaf to a newly sprouted goldenrod, where it eats its way through a bud and into the stem.  The goldenrod plant reacts to this activity by forming an elliptical swelling, or gall, around the area where the larva took up residence. The larva feeds and develops all summer.  Prior to pupating, it chews a tunnel all the way through the gall (this is the only stage in which the moth has chewing mouthparts), and then spins a silk cover for it.  The larva then returns to the cavity in the middle of the gall and pupates.  In the fall the adult moth crawls down the tunnel,  bursts through the thin layer of silk and then mates and lays eggs.


Giant Swallowtail Caterpillar Defenses

The Giant Swallowtail (Papilio crestphones) appears to be extending its range northward into Vermont.  It was first confirmed here two years ago, and more sightings have been made each summer since then.  The Giant Swallowtail is the largest butterfly in North America, with roughly a 4-6-inch wingspan. Because of the caterpillar’s preference for plants in the citrus family, this butterfly is generally is found further south.  However,  Prickly Ash (Zanthoxylum americanum) is found in northern New England, and it is a member of the citrus family.  With this food source, and increasingly warm winters, the Giant Swallowtail may be here to stay.  The larval stage, or caterpillar, is as, or more, impressive as the adult butterfly.  Its defense mechanisms have to be seen to be believed.  The caterpillar looks exactly like a bird dropping (it even appears shiny and wet), making it appear unpalatable to most insect-eaters.   As if that weren’t enough, when and if it is threatened, a bright red, forked structure called an osmeterium emerges from its “forehead” and a very distinctive and apparently repelling odor to insect-eaters, is emitted.


Hickory Tussock Moth

 

Most tussock moths, such as this Hickory Tussock Moth (Lophocampa caryae), are densely covered with hair-like structures called setae that bear microscopic barbs.  Many people are sensitive to these setae and get an itchy rash if they handle a Hickory Tussock Moth.   Even touching the cocoon of a tussock moth can cause irritation, as the setae are woven into it.  Many tussock moths display warning coloration with their black, white, red, orange or yellow setae.  What looks like two Hickory Tussock Moth larvae in the photograph is actually one adult caterpillar (left) and its shed skin (right).   You can find these larvae feeding on hickory, walnut, ash, oak and many other trees in the woods right now.  After spending the winter pupating in a cocoon in the leaf litter, a small spotted, tan moth emerges.


American Lady Larva

The American Lady larva is very distinctive with its branched spines and white bands across its abdomen.  One of its favorite foods is Pussytoes, a member of the Aster family.  The larva feeds inside a shelter it makes by tying up several leaves with silk.  In the photograph, the larva has incorporated the flower heads of Pussytoes into its shelter.  Not only is the larva feeding and growing inside this 1 ½ ”-long  cavity, it also shed its skin.  To see an adult American Lady butterfly, go to http://naturallycuriouswithmaryholland.wordpress.com/2012/07/08/american-lady-common-milkweed-pollinia/ .  Soon after the larva forms a chrysalis and pupates, a butterfly emerges and starts its migration south for the winter.


Tobacco Hornworms & Brachonid Wasps

Tobacco Hornworms, Manduca sexta (often found feeding on tomato plants and confused with Tomato Hornworms, Manduca quinquemaculata) are often the target of a species of Brachonid wasp that parasitizes beetle, moth, fly and sawfly larvae. The adult wasp lays her eggs inside the hornworm with her long ovipositor. The eggs hatch and the wasp larvae feed on the caterpillar. Eventually the wasp larvae emerge and form white pupa cases on the skin of the dying hornworm larva, inside of which they transform into winged adults. Braconid wasps are extremely good at locating hornworms, even when there are very few to find. Because they parasitize hornworm, cabbage worm, aphid and gypsy moth larvae, Braconid wasps are considered important biological control agents. If you want to discourage Tobacco Hornworms in your tomato patch, allow the wasps to complete their metamorphosis – this accomplishes both the demise of the hornworm, as well as an increased population of Braconid wasps.


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