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Archive for August, 2014

Braconid Wasps Pupating and Emerging

8-29-14 braconid wasps 010Tobacco Hornworms, Manduca sexta (often found feeding on tomato plants and confused with Tomato Hornworms, Manduca quinquemaculata) are often the target of a species of a Braconid wasp (Cotesia congregata) 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 spin silk pupa cases (cocoons) on the skin of the dying hornworm caterpillar, inside of which they transform into winged adults within four to eight days. 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. (Thanks to Emily and Joe Silver for photo op.)

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Common Nighthawks Migrating

8-28-14 common nighthawk_w725_h486Nightjars, or “goatsuckers” as some call them, are a family of birds that catch and eat insects on the wing, are often ground nesters, and many (whip-poor-will, for instance) have distinctive calls. Nighthawks are a member of this group, but not a very well-named member, as they are unrelated to hawks and are active at dawn and dusk (not night). This insect-eating bird is often seen on the wing, hawking insects in both rural and urban areas (Fenway Park comes to mind). Its loud, nasal “peent” calls and bat-like flight make this bird very noticeable if it is feeding. We are currently at the peak of the fall Common Nighthawk migration from North to South America. Flocks of hundreds and sometimes thousands are seen flying overhead, often in the early evening.

Unfortunately, in the past 30 years the breeding population of Common Nighthawks in Vermont has declined by 91%, according to the most recent Vermont Breeding Bird Atlas, and this drop in population is not limited to Vermont – much of Canada, New England and beyond has experienced a 50% – 70% decline. Increased predation, indiscriminate use of pesticides leading to lowered insect numbers and habitat loss may have played a part in this drop. (Photo from public domain.)

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Dragonflies Laying Eggs

8-27-14  black-tipped darner 133Never let it be said that Naturally Curious readers aren’t creative thinkers (see guesses on yesterday’s post) ! The vertical slits in the cattail leaves were made by female dragonflies that were in the process of laying their eggs. There are many different egg-laying strategies employed by dragonflies. Many females in the group of large, strong-flying dragonflies known as “darners” (such as the pictured Black-tipped Darner, Aeshna tuberculifera) use their lance-like ovipositors (see photo) to insert eggs into plants stems such as cattail, sphagnum moss, rotting wood or wet soil. However, most species of dragonflies possess non-functional ovipositors. The eggs of many of these species are washed off into water during flight as the female dips the tip of her abdomen into the lake, pond, river or stream.

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Mystery Photo

8-26-14 mystery blog 230Do you know what made the vertical marks on these cattail leaves? All guesses welcome (under “comments”) – Tomorrow’s post will reveal the answer.


Black Bear Scats Reveal Diet

8-25-14  black bear blueberry scat 062Black Bears are eating heavily now, in preparation for the coming winter when they will not eat or drink for several months. Some of what goes in must come out, however, and it can tell you a lot about the diet of an animal. Black bear scats typically weigh ½ to 1 pound or more. They have different shapes and consistencies, depending on what the bear has eaten. Black bear scats may be tubular or loose, depending on the amount of moisture in the food that the bear ate. Scat from succulent vegetation or berries is typically loose. Interestingly, black bear scats do not have an unpleasant smell if the bears ate only fruit, nuts, acorns, or vegetation — they smell like a slightly fermented version of whatever the bear ate.

At this time of year, Blackberries, Wild Sarsaparilla fruit and Blueberries are ripe and favored by bears. You can determine what a bear has been eating by the shape and size of the seeds in its scat. (A bear’s scat can consist of just one type of fruit if there is an ample supply of that fruit.) Wild Sarsaparilla seeds are crescent shaped, Blueberry seeds are tiny and sand-like, and Blackberry seeds are larger than Blueberry seeds. Blueberry scat (pictured) usually includes whole berries that were not soft and ripe enough to be broken up in the bear’s stomach. Bears hardly stop to chew berries. Instead, they swallow them whole and let the muscular, gizzard-like section of their stomach grind the pulp off the seeds. (Thanks to Jeannie Killam for photo op.)

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Goldenrod Bunch Gall

goldenrod bunch gall 144Galls are abnormal plant growths that are caused by a number of agents, including insects. Each gall-making insect has a specific host plant and location (leaf, stem, bud) on which it lays its eggs in the spring, during the growing season. The egg-laying and/or hatching and chewing of the larva causes the plant to react by forming a growth around the insect. Galls of different species of insects vary in their shape and the gall maker can often be identified as a result of this.

Goldenrods are host to about 50 species of gall-making insects, two-thirds of which are midges, or tiny flies. Goldenrod Bunch Galls, also called Rosette Galls, are the result of an egg being laid in the topmost leaf bud of Canada Goldenrod, Solidago canadensis by a midge in the genus Rhopalomyia, often Rhopalomyia solidaginis. The stem of the goldenrod stops growing, but the leaves don’t. The resulting rosette of leaves provides shelter and food for the midge larva, as well as a host of other insects, including other midges. Adult Goldenrod Bunch Gall midges emerge from the galls in the fall, and females lay eggs in the soil. The larvae hatch within one to two weeks and spend the winter underground, emerging in the spring to start the cycle all over again. Interestingly, Rhopalomyia solidaginis lays all male or all female eggs, one or the other.

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Grasshoppers Courting, Mating & Laying Eggs

8-20-14 mating grasshoppers 040It’s that time of year again, when grasshoppers are courting, mating and laying eggs that will overwinter and hatch next spring. In addition to adopting different poses and flashing brightly-colored wings, male grasshoppers attract females by producing calling songs. (Some females also produce sounds, but they are usually infrequent and very soft.) The males rub their hind femur against a forewing, or rub a forewing against a hind wing in order to make their calls, a process called stridulation. Tympana, or eardrum-like structures on their abdomen, allow both male and female grasshoppers to hear. Because the songs are species-specific, females can readily identify males of the same species.

After pairing up, the smaller male grasshopper usually mounts the female and the female curls her abdomen up to reach the male’s reproductive organ (aedeagus) from which she receives a package of sperm called a spermatophore. The mating process can take from 45 minutes to more than a day, depending on the species. The small, pointed structures that you see at the tip of the female’s abdomen are her ovipositors, with which she deposits her eggs in the ground.

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Raccoons Quick and Adept Hunters

raccoon pond scat 134Not everyone enjoys discovering what an animal eats by dissecting its scat, but for those of us who do, the revelations can be worth the effort. One quick glance at the shape and size of the pictured scat confirmed that a raccoon had been in the vicinity and bits of crayfish exoskeleton in it indicated that the raccoon fed from the nearby pond. Further examination of the contents revealed that raccoons are fast enough to catch dragonflies – something I wouldn’t have necessarily known and most likely wouldn’t observe in the field. Who would have guessed that raccoons are quick enough or interested enough in dragonflies to catch them? (NB: Do not do as I did – do not touch or dissect raccoon scat as it can contain bacteria, ticks and Baylisascaris roundworms which can cause neurological damage.)

As an aside, I thought it might be of interest for readers to know what goes into the making of a Naturally Curious post. The following describes my morning yesterday: out for a walk, visit a pond, see scat on a big, wooden raft that has floated near shore, manage to leap onto raft to take a picture of the scat, photograph scat and then look up to see that my leap has shoved the raft away from the edge of the pond, and I’ve drifted out into the middle of said pond. Balancing the camera on the raft, I paddle, first with one hand and then with both (at one corner), trying to move this 15’ x 15’ wooden structure in the direction I want it to go. Make a little progress, but not much. Beloved chocolate lab swims up to raft, I hold onto her neck and she pulls us to shore, camera intact. And I haven’t even begun to dissect, photograph, label and write about the contents of what led me on this adventure!

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Young Cooper’s Hawks Fledging

8-19-14 juvenile cooper's hawk2 306After a month of living in a nest that measures roughly 7 ½ inches across and 3 inches deep, Cooper’s Hawk nestlings are more than ready to stretch their wings. Although they’ve been dismembering prey (mostly birds and a few small mammals brought to them by their parents) since they were three weeks old, catching prey is a skill they have yet to acquire. For roughly ten days after they leave their nest, the young hawks return to it for continued prey deliveries (and for roosting). During this time the fledglings learn to catch their own prey and they become independent, but they continue to stay together near their nest for the next month or so. (Thanks to Marian Boudreault for photo op.)

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Second Brood of Woolly Bears Hatches

8-18-14  woolly bear 093Typically we start seeing Woolly Bear caterpillars in October, when they are searching for sheltered spots in which to spend the winter as larvae. With only two months between now and then, it came as a surprise when my great nephew and budding naturalist Eli Holland discovered a very young Woolly Bear recently. It turns out that in New England, there are two broods of Isabella Tiger Moths (whose larval stage is the Woolly Bear). The caterpillars that hibernated last winter emerged from hibernation this past spring, pupated, transformed into adult Isabella Tiger Moths, and proceeded to mate and lay eggs. It is these eggs that have recently hatched, and the Woolly Bear caterpillars that are no bigger than the length of your baby fingernail right now will be eating dandelions, grasses, nettle and meadowsweet nonstop for the next two months in order to survive the coming winter.

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Common Gartersnakes Giving Birth

8-15-14  common gartersnake 082Common Gartersnakes mate soon after emerging from hibernation in the spring, in March or April, and four months later the females give birth to live young. The newborn snakes are 5 to 9 inches long at birth and from day one have to fend for themselves. Their diet at this early stage consists of earthworms, insects, slugs, tadpoles, small frogs and fish. If there is an abundant supply of food, the young snakes can grow as much as 1 ½ inches a month during their first year. Earthworms are their preferred diet and gartersnakes are known for their ability to find them, even underground. It turns out that earthworms produce a chemical substance in their skin that is easily detected by (and attractive to) Common Gartersnakes. (Thanks to Eli Holland, who located the worm-eating newborn Common Gartersnake in the photograph.)

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Antlions Trapping Insects

8-14-14  antlions - 230The larvae of a predaceous group of winged insects (family Myrmeleontidae) that closely resemble dragonflies and damselflies are referred to as “antlions” – they have the ferociousness of a lion and prey mainly on ants. The manner in which an antlion traps its prey is ingenious. It excavates a conical pit in sandy soil (an antlion is also called a “doodlebug” because of the squiggly trails it leaves in the sand looking for just the right spot for a pit). Using its head as a shovel, it tosses out sand as it turns in a circle, digging deeper and deeper, until it forms a pit roughly two inches deep and three inches wide. The antlion lies at the bottom of the pit, covered by a thin layer of sand except for it pincer-like mandibles, which are ready to snatch prey at a second’s notice.

The slope of the sides of the pit is at the angle of repose – as steep as it can be without giving way – so when an ant accidentally steps over the edge of the pit and falls in, the sand beneath it collapses, carrying the ant to the bottom of the pit and into the pincers of the waiting antlion. If the ant tries to scramble up and out of the pit, the antlion tosses a load of sand at the ant, knocking it back down. The antlion then injects venom and digestive fluids into the prey via grooves in its mandibles, and drinks the innards of the ant through these same grooves.

The antlion’s anatomy is as unusual as its method of capturing prey. It has a mouth cavity, but no mouth opening, and no external opening for solid waste. Because digestion takes place outside of its body, the antlion doesn’t accumulate a lot of waste, but what it does accumulate stays inside of it until the antlion matures into an adult. This can be anywhere from one to three years, depending on the species. When fully developed, the antlion constructs a small, round pupal case out of silk and sand, in which it overwinters. It emerges from this case the following spring as a winged adult. (Thanks to Joan Waltermire and John Douglas for photo op.)

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“Elfin Saddle” Fungi Fruiting

smooth-stalked helvellaIMG_1997A group of fungi called the Ascomycetes, or sac fungi, all produce their spores in sac-like structures. This group includes, among others, morels, false morels, cup fungi and saddle fungi. Sac fungi in the genus Helvella are known as “Elfin Saddles” — the caps of their fruiting bodies come in a variety of shapes, including ears and cups as well as saddles. Most are not brightly colored and are usually white, cream, buff, brown, gray or black. Helvella species grow on the ground or, in a few cases, on rotting wood. Species are defined by the shape of their caps and the texture of their outer surface and stem. (Thanks to Susan and Dean Greenberg for photo op.)

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Two-month old Common Loon Chick Beginning to Look Like a Loon!

8-12-14 c.loon two months old IMG_8704Remember that little black ball of fluff that was featured in Naturally Curious loon posts two months ago? That downy Common Loon chick has lost both its black and its brown coat of down, and is now covered with smooth, gray contour feathers. Nearly the size of its parents, it is looking quite sleek. Soon the chick’s flight feathers will be completely in. In only a matter of two or three more weeks it will be flapping its wings and making take-off runs in preparation for flight, which it will be capable of in another month. (It will be two years old before it attains adult plumage.)

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Great Golden Digger Wasps Digging Nests & Provisioning Them with Food

8-11-15 great golden d.w.2 159The Great Golden Digger Wasp, Sphex ichneumoneus, is a solitary, predatory wasp whose hunting and nesting techniques are programmed and never vary. Having overwintered underground in a nest dug by its mother, the adult wasp emerges, often in August, and begins preparations for the next generation. She digs several nests in packed, sandy soil, using her mandibles to cut the earth. Emerging backwards from the ground with a lump of soil between her forelegs and head, she flips the soil with her forelegs beneath her body, scattering it to the sides with her hind legs. In this manner she excavates several cells off a central 4-6-inch deep tunnel.

The wasp seeks out prey — often a grasshopper, cicada or cricket – and then stings and paralyzes it. If the prey is small, she flies it directly to the nest. If prey is too large to transport aerially, the wasp will walk with it across the ground, dragging it by its antennae (see photo). She then drops the prey several inches from the nest hole. After crawling down into the nest for a brief inspection, she pulls the prey down into one of the cells while walking backwards. She then leaves to find another insect. When a cell contains paralyzed prey, the wasp lays an egg on the insect. The egg hatches within two or three days and the wasp larva begins eating the insect. Because the prey is not dead, decomposition is delayed, and the wasp larva’s food is relatively fresh. The developing wasps overwinter in the nest and emerge the following summer to begin the process all over again.

If you live near a sunny area of compacted clay and sand that has flower nectar for adults to feed on and crickets, grasshoppers and katydids for their larvae, you may well have a chance to observe this unique ritual. (Thanks to Marian Cawley for photo op.)

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Myrmecochory: Seed Dispersal by Ants

8-6-14  myrmecochory 014As a dispersal mechanism, some plants have fatty structures called elaiosomes attached to their seeds’ coats which are very appealing to ants. After collecting a seed and carrying it back to its underground nest, the ant eats the elaiosome (or feeds it to ant larvae) and discards the intact seed in an area where waste and dead ant bodies are stored. Germination is highly likely in such an ideal environment, making myrmecochory a win-win situation. Trillium, bloodroot and violets are some of the thousands of plants that have elaiosomes attached to their seeds.

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Broad-winged Hawks Become Empty-Nesters

8-7-14 broad-winged fledgling2 037Broad-winged Hawk nestlings typically leave their nest sometime in July or early August, at about five to six weeks of age. The fledglings tend to stay within their parents’ territory for up to eight weeks. Much of the first two weeks after fledging is spent perched close to the nest, often returning to the nest for food delivered by the parents, but by the time the fledglings are about seven weeks old, they are capturing their own prey. This leaves the adults free to hunt for themselves, as they fly overhead emitting their high-pitched, shrill whistle. (Photos: adult Broad-winged Hawk)

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Robber Fly Mimics Bumblebee

8-4-14  robber fly like bumblebee2 054Milkweed leaves make excellent platforms for all kinds of insects, particularly those such as dragonflies and robber flies, which sit, wait and watch, surveying the landscape for prey to ambush. This robber fly could quite easily be mistaken for a bumblebee. However, the short, straight antennae and the presence of only two wings (instead of four) tell you it’s in the order Diptera (true flies). The pointed, stout proboscis, bearded face, fleshy feet and long, tapering abdomen narrow it down to a species of robber fly. Robber flies in the genus Laphria resemble bumblebees – they are typically quite hairy, with black bodies and yellow stripes on their abdomens. Like other species of robber flies, they hunt by perching and snagging prey such as other robber flies, bees, wasps or beetles. They often return to their perch, inject the prey with enzymes that dissolve its innards, and then have a long drink. Why mimic a bumblebee? To deceive unsuspecting honeybees, wasps and other insects that would make a good meal.

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Young Beavers Out and About

8-5-14 adult and young beaver2 082Most beavers are born between May and early July, weighing one pound and measuring a foot long. They are fully furred, their eyes and ears are open and they know how to swim. Even so, they don’t usually venture out of the lodge for the first month or so. Initially their fur isn’t water-repellent, but by three to four weeks of age, the young beavers’ anal glands, used in greasing their fur, are functional. When the kits weigh seven or eight pounds, they start to leave the lodge regularly to explore their pond and feed with their parents and older siblings.

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Clymene Moths Active

8-4-14 Clymene moth 140The Clymene Moth, Haploa clymene, is noted for the striking upside-down cross pattern on its forewings. Because of this design, some people refer to it as the “Crusader Moth.” A member of the Tiger Moth family (as is the Woolly Bear/Isabella Tiger Moth), the Clymene Moth can be seen flying day or night. Typically they inhabit deciduous forests and fields adjacent to them where the black, bristly larvae feed on a wide variety of plants, including willows, oaks, and members of the Aster family. In contrast to its white forewings, the Clymene Moth’s hind pair of wings is bright yellow. Its long proboscis allows it to reach deep inside the nectar-bearing hoods of Common Milkweed.

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Ordering Information for “Island Naturalist”

You can order Kathie Fiveash’s book, “Island Naturalist” at http://www.penbaypress.me or on Amazon.


Maine Naturalist Publishes Book of Seasonal Essays

Island Naturalist coverA fellow naturalist and faithful follower of the Naturally Curious blog , Kathie Fiveash has compiled four years of her natural history columns about the Maine coastal environment into a recently-published book entitled Island Naturalist. Penobscot Books, the publisher, describes it in the following way:

“Fiveash’s essays take the reader among the flora and fauna of the rocky shores, spruce forests, bogs, meadows, clam flats, ponds, streams, marshes and ocean of coastal Maine. While she writes from Isle au Haut, the information she provides is pertinent to all of coastal Maine.

The book is laid out by season, beginning in spring with writings about mud season, spring peepers, robins and dandelions. Summer brings baby birds, fireflies, monarch butterflies and lichens. Featured in fall are apples, bird migration, harbor seals and lobsters. Winter closes the year with scallops, sea ducks, life beneath the snow and winter solstice…”

I wanted to make readers of my blog aware of this publication, as it is similar in nature to Naturally Curious and therefore likely to be of interest to some of you — a great introduction to the ecology of the Maine coast through the eyes of a gifted naturalist.


Tortoise Beetle Larvae Making Fecal Shields

8-1-14  tortoise beetle larva with fecal shield 049Instead of discarding feces, or frass, some insects save their waste matter for defensive purposes such as “fecal shields.” These are coverings over the back of the larvae that are made largely of feces and provide either physical or chemical barriers to predation. Adult Tortoise Beetles have a type of shield (hence, their name), but it is formed from expanded, hardened forewings, and is not a fecal shield. The larvae of these beetles have fecal shields which serve as chemical deterrents, preventing most predators from even touching them. The deterrent in the feces comes from the beetles’ food source — plants in the order Solanales. Tortoise Beetle larvae have what is known as a “fecal fork” on their last abdominal segment, which they hold over their body. The larvae maneuvers its muscular, telescopic anus, or “anal turret” in such a manner as to excrete its feces and bits of shed exoskeleton onto the fecal fork, forming an umbrella-like fecal shield.

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