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Larvae

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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Willow Beaked-Gall Midge

10-30-13 willow beaked-gall midge   047Now that most of the leaves have fallen, it’s a good time to look for galls that form on woody plants. Willows are host to a great number of gall-making insects, including tiny flies called midges. The most common species of willow gall midge is the Willow Beaked-Gall Midge, Rabdophaga rididae. In the spring, after mating, the adult female midge lays an egg in a willow bud (often terminal) that is just starting to expand. The egg soon hatches and the larva burrows deeper into the bud, which causes the bud tissue to swell and form a gall, usually with a “beak” at the top. The larva remains inside the gall through the winter, where it has a constant supply of food (the interior of the gall) and shelter. In the spring the larva pupates, and an adult midge emerges and begins the cycle all over again. Some gall midges are crop pests, but willows are not significantly damaged by the Willow Beaked-Ball Midge.

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Jewelweed Gall Midges

10-4-13 jewelweed gall  277Abnormal plant growths called galls come in all sizes and shapes, are found on leaves, buds and stems, and are caused by a number of agents, including insects. A majority of insect galls are caused by the eggs and developing larvae of flies, wasps and midges. Jewelweed, or Touch-Me-Not (Impatiens capensis), has a very distinctive looking aborted bud gall that is produced by a midge (Schizomyia impatientis). While some galls provide shelter and food for a lone resident, the Jewelweed Gall Midge is colonial, and several orange larvae can be found residing in separate cavities within the gall. These midge larvae are now emerging and will overwinter as adults.

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Apple Scat

10-4-13 woolly bear scat 028At this time of year it’s not unusual to find the scat of various mammals consisting mostly of apple. Red Foxes, White-tailed Deer, Cottontail Rabbits, Porcupines and Black Bears, in particular, are all avid consumers of this appetizing fruit. Birds, including Purple Finches, Cedar Waxwings and Northern Mockingbirds, also include apples in their diets . While many insects drink the juice of apples, it’s not that often you see an insect like this Woolly Bear caterpillar (the larval stage of the Isabella Tiger Moth) consuming a sizable chunk of a McIntosh apple and leaving behind tell-tale scat. (Discovery by Sadie Richards)

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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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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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Cerceris fumipennis: a biosurveillance tool for the emerald ash borer

8-19-13 Cerceris wasp with beetle prey2 099While we’re more familiar with social wasps, such as paper wasps, yellow jackets and hornets, there are also parasitic and solitary wasps. Solitary wasps live alone (as their name implies), all the females (not just the queen) are fertile and they are predatory. Among them is a wasp, Cerceris fumipennis, which preys exclusively on the family of beetles (Buprestidae) to which the Emerald Ash Borer (EAB), the invasive beetle that’s threatening the ash tree population, belongs. After catching and paralyzing its prey, the wasp carries it back to her larvae in the nest she’s dug underground. A biosurveillance program exists which involves monitoring the prey that this species of wasp collects and brings back to the nest, in order to detect the presence of the Emerald Ash Borer in any given area. (This is how the EAB was first detected in Connecticut.) Pictured is a Cerceris fumipennis wasp with a Buprestid beetle (not an EAB) prey. (To become involved in Vermont’s citizen science biosurveillance program next summer, contact entomologist Trish Hanson of the Vermont Dept. of Forests, Parks and Recreation at Hanson.Trish@state.vt.us .)

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The Give and Take of Food in a Paper Wasp Nest

8-7-13  paper wasp nest 011Like all adult wasps, bees, and ants, adult paper wasps are limited to liquid diets – they have no chewing mouthparts, and the passageway between their head and abdomen, where food is digested, is so narrow that pieces of food wouldn’t fit through it. Wasp larvae (the white grub-like organisms in the upper third of the pictured wasp nest cells) are able to eat a wider range of food, due to mouthparts and their body structure. Adult paper wasps capture and feed caterpillars and other insects to their larvae. The larvae then digest their food and produce saliva rich in nutrients. The adult wasp proceeds to scrape her abdomen across the nest, producing a vibration that signals to the larvae to release some of their carbohydrate-rich saliva which the adult then drinks. (Cells covered with white paper nest material contain wasp pupae.)

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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.


Caterpillar Survival Strategies

6-14-13 camouflaged catterpillar 049The larvae of moths and butterflies are very susceptible to predation, especially by birds, and they utilize many different strategies to protect themselves. Shapes, colors and behavior all contribute to their survival. Some larvae take on the appearance of less appetizing things, such as bird droppings, twigs or leaves. Some have large eye spots which presumably scare predators. Others have cryptic coloration which makes them all but invisible. The pictured green caterpillar uses both color and behavior to visually disappear on the fern it is consuming.


Hairy Woodpeckers Raising Young

6-3-13 hairy woodpecker looking right 330The chipping of hungry Hairy Woodpecker nestlings can easily be detected by human ears, even though it comes from deep within a tree cavity. One is reminded of how beneficial this species is when observing the steady delivery of food by these woodpeckers to their young. More than 75% of an adult Hairy Woodpecker’s diet consists of injurious insects, while the amount of useful insects and cultivated fruits that they destroy is insignificant. Beetle larvae (mostly wood-boring) make up 30% of the insects that are consumed, with ants ranking second, at 17%. Caterpillars, such as those pictured, comprise about 10% of an adult Hairy Woodpecker’s diet, but given this parent’s beakful, one wonders if the percentage is greater for nestlings.


Sawfly Larva

5-31-13 sawfly larva 266Although it looks like a caterpillar, this larva is not going to metamorphose into a butterfly or moth. This is because it is a sawfly larva, and is closely related to bees and wasps. (It gets its name from the adult female’s saw-like, egg-laying ovipositor that opens like a jack-knife from the tip of her abdomen.)There are several ways to distinguish between these two types of larvae (sawflies and butterflies/moths). While both have three pairs of true legs on their thorax, caterpillars (larvae of moths and butterflies) have up to five pairs of prolegs (fleshy structures that resemble legs) located on their abdomen behind their true legs, while sawfly larvae have six or more pairs. A closer look at the tips of the prolegs on caterpillars will reveal tiny hooks called “crochets,” which are lacking on sawfly larvae prolegs. Sawfly larvae also exhibit distinctive behavior. If you see something that looks like a caterpillar feeding along the margin of a leaf and it rears up its hind end when disturbed (perhaps to frighten predators), chances are great that you are looking at a sawfly larva.


White Admiral/Red-spotted Purple Caterpillars Emerge from Hibernation

5-15-13 white admiral larva 133Butterflies 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!


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!


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.)


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.


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.


Black Bear Signs & Hyperphagia

Black bears are omnivores as well as opportunists.  They will eat almost anything that they can find, but the majority of their diet consists of  grasses, roots, berries, nuts and insects (particularly the larvae).  In the fall, prior to going into hibernation, black bears enter a stage called “hyperphagia,” which literally means “excessive eating.”  They forage practically non-stop — up to 20 hours a day, building up fat reserves for hibernation, increasing their body weight by 35% in some cases.  Their daily food intake goes from 8,000 to 15-20,000 calories (that’s roughly equivalent to 70 McDonald’s cheeseburgers).  Signs of their foraging for grubs and beetles, such as the excavated base of the snag in the photograph, can be found with relative ease at this time of year, if you live where there are black bears.  If you do share their territory with them, be forewarned that they have excellent memories, especially for food sources.  Be sure not to leave food scraps or pet food outside (my compost bin was destroyed last year but I have no solution for that particular problem), and if you really don’t want any ursine visitors, it’s best to not start feeding birds until most black bears have entered hibernation – late December would be safe most years.


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.


Signs of Striped Skunks

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If you are finding small, conical pits in your lawn, you probably have a striped skunk to thank for reducing your grub population.  During the spring and summer, invertebrates make up a large percentage of this nocturnal omnivore’s diet.  With the help of their well-developed sense of smell and their long nails (which make them excellent diggers), they locate, gain access to and consume subterranean insect larvae with relative ease.   Another sign of skunk activity, in addition to lawn divots, are the excavated ground nests of yellowjackets.  If they’ve met with success, skunks will often leave sections of empty, paper cells scattered about the nest site.  Apparently, even though yellowjackets can sting multiple times, they’re not very effective at discouraging foraging skunks.  Should you be so inclined, a close examination of skunk scat will reveal bits of insect exoskeletons, as well as the bones and hair of small rodents.  The pictured scat (next to the divot) contained, in addition to insect parts, the fur of another nocturnal animal, a flying squirrel.  (Thanks to Emily and Joe Silver for photo op.)


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.


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