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Invertebrates

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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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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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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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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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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Scarab Beetle Antennae

6-16-14  scarab beetle antennae 261Beetles in the family Scarabaeidae share several characteristics, including specialized antennae. The last three to seven segments of each antenna form flat plates, or lamellae, that can be expanded like a fan (see Japanese Beetle insert) or folded together into a club (see June Beetle photo). When these plates are separated they are being used as sensory devices to detect odors. When folded together, the antennae are used as clubs by some species of fighting male scarabs. The next time you see a June Beetle, Rose Chafer or Japanese Beetle, take a second to inspect its antennae before parting company.

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Eastern and Canadian Tiger Swallowtails

6-16-14 Canadian Tiger SwallowtailSwallowtails are North America’s largest butterflies, and their tropical relatives are the largest butterflies in the world. At this time of year, Tiger Swallowtails emerge from their chrysalises and seek nectar wherever they can find it, often in gardens. The two common species in the Northeast are the Eastern Tiger Swallowtail and the Canadian Tiger Swallowtail. Those of us living in northern New England are most apt to see the Canadian Tiger Swallowtail, which replaces the Easter Tiger Swallowtail this far north. Both species can be found further south. There are ways to tell these two swallowtails apart (although sometimes where their ranges meet, it can be difficult). The Canadian Tiger Swallowtail is smaller than the Eastern Tiger Swallowtail, but unless you have them side-by-side, this isn’t all that helpful. The easiest way to tell the two species apart is to look on the underside of the butterfly’s forewing and see if the yellow band along the margin is solid (Canadian Tiger Swallowtail, Papilio canadensis), or if it is broken up into spots (Eastern Tiger Swallowtail, Papilio glaucus). (Photo is of a Canadian Tiger Swallowtail)

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Rosy Maple Moths Emerging

6-9-14 rosy maple moth 161This is the time of year when moths rule the nights. Many moths in the silkmoth family, Saturniidae, emerge in June, including giant silkmoths such as Luna Moths and Cecropia Moths. A smaller member of this family also appears at this time of year. While the 1 to 2-inch Rosy Maple Moth (Dryocampa rubicunda) wingspan doesn’t come close to many of the giant silkmoths’ 5 to 6-inch wingspan, its pink and white or yellow coloring is stunning. Adults emerge mid-May through mid-July in the late afternoon, and they mate in the late evening. Females begin laying eggs at dusk the next day in groups of 10-30 on leaves of the host plants (Red, Sugar and Silver Maples, as well as Box-elder and some oak trees). The eggs hatch in about 2 weeks and the larvae are referred to as Green-striped Mapleworms. They occasionally do considerable damage to their host trees when their population soars. In New England there is only one brood per summer, with the larvae pupating and overwintering underground.

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Jumping Spider Guards Egg Sac

6-5-14 jumping spider2  077Spiders protect their eggs by wrapping them up in a sac they make out of silk. Some species (such as garden, or black-and-yellow argiope, spiders) then die, leaving their egg sac to withstand the elements, as well as potential parasites and predators, on their own. As you would guess, these sacs are usually fairly impenetrable. In other species, female spiders survive long enough to guard their eggs until they hatch, or even until the young spiderlings disperse, and these sacs are usually far less tough. In the species where the female protects her eggs, some females carry their egg sacs with them at all times (wolf spiders, nursery web spiders) while others (jumping spiders) simply remain with the sac. Their excellent eyesight and impressive ability to leap many times their body length gives jumping spiders an advantage over any potential predators. (Photo – jumping spider with egg sac)

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Avian Parents Hard At Work

robin with food 077To appreciate the parental demands on birds, consider the feeding habits of a pair of American Robins with a nest full of young. Both parents feed their 3 – 4 nestlings, delivering 6 – 7 feedings an hour, each one to a single nestling. (Parents tend to arrive with food at a particular location on the nest rim, so there is much jockeying for a position near this spot on the part of the nestlings.) Each nestling gets 35-40 feedings per day. This amounts to almost half a pound of food delivered to the nest every day for the 13 days that young are in the nest. Even then, the parents’ work is not done, as they continue to feed their fledglings for up to three weeks after the young leave the nest.

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Where Do Slugs Spend the Winter?

4-1-14  slug under bark 223Slugs mate and lay eggs in the spring and fall, and can live 12 to 15 months. Eggs laid in the fall overwinter in this stage, and hatch in the spring. Some members of this generation of slugs may die in the fall, while others hibernate underground or beneath loose bark. The survival rate of the hibernators depends upon the harshness of the winter. Look in and under rotting logs to find slug eggs, and behind the bark of dying trees to find slug hibernacula.

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Praying Mantis Egg Case

12-9-13 praying mantis egg case 057In the fall, after mating, the female praying mantis lays up to 400 eggs in a frothy liquid produced by glands in her abdomen. This one to two-inch long mass is attached to vegetation, often grasses and goldenrod stalks, about a foot or two off the ground. The frothy structure hardens, providing a protective case for the eggs. In the spring, miniature (wingless) mantises, called nymphs, will hatch from this egg case. When hatching, the nymphs appear all at once, crawling from between tiny flaps in the case and then hanging from silk threads about two inches below the case. Within an hour or two, after drying out, they disappear into nearby vegetation.

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Backswimmers Active Under Ice

11-18-13  backswimmers under ice 061Backswimmers are insects classified as “true bugs” and belong to the order Hemiptera. Most Hemipterans are land dwelling, such as stink bugs and assassin bugs, but there are a few, such as water striders, water boatmen and backswimmers, that are aquatic. In the fall, when most insect hatches have ceased, backswimmers come into their own. While some hibernate at the bottom of ponds in winter, others remain active, sculling through the water with their oar-like hind legs that are covered with fine hairs, preying on all forms of life up to the size of a small fish. Thanks to bubbles of oxygen that they obtain from pockets of air just under the ice and carry around with them like mini aqua lungs, backswimmers can continue to stay below the surface of the water for several minutes. Like most aquatic insects, backswimmers supercool their bodies (produce antifreeze compounds called cryprotectants that allow their body fluid to go down to 26 to 19 degrees F. without freezing). Right now, when there’s a thin layer of ice on most ponds and no snow covering it, you might want to peer through the ice at the edge of the pond to see if you can locate any of these cold-hardy creatures. Just be sure you don’t fall in, as I did two seconds after this photograph was taken. My undying gratitude for those of you who have donated to Naturally Curious, as your support enabled me to replace both camera and lens!

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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


Woolly Aphids

10-8-13 woolly aphid 001Woolly aphids are just that – aphids that have special glands that produce wax-like filaments which resemble white wool. When the “wool” is brushed aside, the dark aphid bodies below are apparent. Colonies of woolly aphids often congregate in cottony masses while sucking the sap of a host plant or tree, at which time they are somewhat camouflaged in that they can easily be mistaken for mold or a fungus. When woolly aphids take flight, the wax strands catch the wind and allow them to drift , allowing them to look more like seeds than edible prey.

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Grasshoppers Mating and Laying Eggs

9-23-13 mating grasshoppers 137Grasshoppers typically mate in late summer and fall. If it’s a short-horned grasshopper (pictured), the smaller male mounts the female (female long-horned grasshoppers mount the males). The male short-horned grasshopper often remains riding the female for long periods in order to ensure paternity. When the eggs are fully formed, the female pushes the ovipositor at the end of her abdomen ½” to 2” into the ground and produces a glue-like secretion that cements the soil around the egg mass, forming a protective “pod.” Each pod may contain 25 to 150 eggs, depending on the species of grasshopper. Grasshoppers which deposit masses containing few eggs usually lay more pods to compensate. A female may lay as many as 300 eggs which overwinter and hatch in the spring.

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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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How Slugs Eat

9-18-13 slug radula 262No-one needs a description of the damage that slugs can do in a garden, but the exact way in which they do the damage is quite unique. They actually do not have mouthparts as such, nor do they possess teeth as we know them. They, like most molluscs, have a radula, or rasping tongue-like organ with which they procure food. A bit of cartilage, the odontophore, forms the core of the radula. The rest of the radula consists of a band, similar to a conveyor-belt, covered with thousands of tiny tooth-like protrusions called denticles. The band moves over the odontophore, rasping away particles of food and moving them back into the slug’s gullet. The pictured slug was making short work of a mushroom.

ADDENDUM TO YESTERDAY’S POST: After several reader comments and self-reflection, I’ve come to the conclusion that yesterday’s post could well be black bear, not raccoon, vomit. While all I found in the cornfield were signs of raccoons, it was a huge field, and I may have just missed bear sign or the bear may well have visited another field prior to getting sick. The amount of vomit was so large that it would have taken a giant raccoon to have left it. Both of these animals feed voraciously in the fall in preparation for winter — black bears can double their weight prior to denning.

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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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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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Sundews Capture Their Meals

8-12-13 sundew & damselfly 060Sundews (Drosera spp.) are carnivorous plants often found in acidic bogs, fens and cedar swamps. They have numerous small leaves arranged in a circular, or rosette, pattern and they are covered with reddish, glandular hairs, or tentacles, that exude a sticky secretion at their tips. Insects, attracted to the glistening sticky droplets which resemble dew, land on a leaf and become stuck. The movement of the struggling insect triggers cell growth in the glandular hairs and they begin folding over the insect within 60 seconds. An anesthetic is released by the plant’s hairs, causing the insect to become motionless. Digestive enzymes are then secreted which liquefy the insect’s internal organs so that they can then be absorbed by the plant’s hairs. Although insect prey is not vital to sundews, the nitrogen the plants receive from the insects enables them to thrive in environments where nitrogen is in short supply. The damselfly pictured has been captured by a Round-leaved Sundew’s glandular hairs which have rendered it motionless and have started to grow and fold over the tip of the damselfly’s abdomen and its wings.

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Clean Antennae Necessary for Sensory Perception

8-9-13 conehead katydid cleaning antenna 098Insect antennae are among the most sensitive and selective chemical-sensing organs in the animal kingdom. They detect information crucial to an insect’s survival, including odors, sounds, humidity, changes in water vapor concentration and air speed. Antennae are capable of these feats because of the sensory receptors covering them which bind to free-floating molecules. Experiments with cockroaches, ants and flies confirm that insects engage in antennal grooming — removing foreign materials from the surface of their antennae with their mandibles — primarily to maintain acute olfactory reception. Pheromones, chemical signals that are vital to insect communication, are used to convey alarm, attract a mate, mark territory and lay out trails, among other things, and clean antennae enhance these messages. (Photo is of a Sword-bearing Conehead Katydid cleaning its antenna.)

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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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Harvestmen

8-1-13 daddylonglegs 148Harvestmen (daddy longlegs) and spiders are closely related and share many characteristics, but they also have significant differences. One such difference is that Harvestmen do not possess venom glands, nor the digestive enzymes capable of breaking down the insides of prey into a liquid. (Some species of Harvestmen are omnivores, eating both plant and animal matter, others are scavengers.) Unlike fellow arachnids (spiders, ticks, scorpions and mites) that drink their food, Harvestmen ingest small particles, breaking them down with their chelicerae, or mouthparts, which resemble miniature, toothed lobster claws. In this photograph, the Harvestman is holding a deer fly with its pedipalps, appendages used to grasp food as well as their mates. Its chelicerae are too small to discern, but they do the job — in the space of about ten minutes, this Harvestman consumed an entire deer fly, bit by bit.

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