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Arthropods

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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Carrion Beetles Feeding

7-30-14 carrion beetle feeding 129When an organism dies, such as the pictured American Toad, a series of decomposers appear and break it down. Some of the first insects to arrive at the scene are blowflies, and they lose no time in laying eggs which rapidly hatch into larvae, or maggots. A bit later, carrion beetles move in. Both of these insects live in dead carcasses, where they eat raw flesh and fungi. There is great competition, believe it or not, for rotting bodies, and carrion beetles such as the pictured American Carrion Beetle (Necrophila americana) have managed to find a way to eliminate some of it. They carry tiny mites on their backs which travel from carcass to carcass with the beetles, devouring the eggs of maggots as well as the smallest maggots themselves. In addition, carrion beetles secrete a strong offensive odor that irritates other insects and predators, a second effective way to reduce the number of insects competing for a corpse.

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Twelve-spotted Tiger Beetle Larva at Work

7-24-14 tiger beetle adult and larva 040Without doubt, I have one of the most erudite readerships in the land of blogs. Several people recognized this uncommon phenomenon. To clear up a few misconceptions, however, being a male, this dragonfly was not laying eggs. Neither was it fertilizing them – male dragonflies perform this act when coupled with a female. This Chalk-fronted Corporal had the misfortune to sun itself on a tiger beetle-inhabited patch of sand. One of the most aggressive groups of insect predators is the tiger beetle family. They are especially known for their speed – up to 5.6 mph, which is comparable to a human running 480 mph. If you watch an adult tiger beetle hunting, you’ll notice that it stops and starts frequently. This is because it runs so fast it goes blind — its brain has trouble processing the information it sees, and the beetle must stop to regain its sight.

The larvae of the Twelve-spotted Tiger Beetle live in tunnels that they dig in the sand (some of you noticed tiny holes near the dragonfly) that can be up to a foot deep. The larvae have hooks located on the back of their abdomen to anchor them to the side of the burrow. Tiger beetle larvae are also predators, and after digging a tunnel the Twelve-spotted Tiger Beetle will crawl up it until just the top of its head is visible. From this position the larva watches for prey wandering by. When it sees a potential meal, such as yesterday’s dragonfly, it flips backwards faster than you can blink an eye and grabs its prey, pulling it down as far as it can into its tunnel, where it safely feasts on its catch. The portion of the Chalk-fronted Corporal’s abdomen that was inside the tiger beetle tunnel was completely consumed except for the outer skeleton.

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Eyed Click Beetle

7-10-14 eyed click beetle 789Although this Eyed Click Beetle (Alaus oculatus) looks ferocious with its large, black “eyespots” (actual eyes are below antennae), it is harmless to humans. Like all members of the click beetle, or Elateridae, family, it gets its name from the sound it makes when it flips itself upright. Click beetles possess a spine-like structure as well as a notch under their thorax. When they release the spine from the notch, it snaps and they are propelled into the air. Click beetles use this mechanism to right themselves if they are on their backs. Entomologists feel predators are deterred not only by the false eyes, but by this action. The larvae, called wireworms, spend most of their life (2 to 5 years) in the soil feeding on decaying plants and other insects in the soil before emerging as adults. (Thanks to Liz Ambros for photo op.)

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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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Paper Wasp Queens Emerging From Hibernation

4-8-14 paper wasp2  152Paper wasps have annual colonies – only the young, fertilized queens overwinter, with the old queen, female workers and the males all perishing in the fall. The queens seek shelter behind tree bark, or in rotting logs or stumps, and emerge in the spring when temperatures rise and day length is increasing. Last year’s nest is not re-used – the queen mixes wood and plant fiber with her saliva, creating several waterproof paper cells into each of which she lays an egg — the start of her future labor force. Due to the lack of wildflowers (and therefore nectar) this early in the spring, queens rely on the sap from broken tree branches, as well as the sap found in drilled Yellow-bellied Sapsucker wells, for sustenance.

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Winter Stoneflies Still Emerging

4-2-14 stonefly 123It seems early, especially with feet of snow still on the ground, to be seeing insects flying around, but some have actually been present all winter. An order of insects (Plecoptera) known as stoneflies spends its youth (one to four years) living in streams before emerging as winged adults. Some of these species, referred to as winter stoneflies, emerge from January through April, providing food for early-returning, insect-eating migrants, such as Eastern Phoebes, Tree Swallows and Red-winged Blackbirds. Stoneflies only live a few weeks, during which time they mate and lay eggs. Some do not feed, and others consume plant material. Because stoneflies are intolerant of polluted water, if you see one it’s a good indication that the water quality of the stream that it came from is excellent.

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Cold Snaps & Hardy Invertebrates

1-14-14 TICK IMG_0528As you may have heard, there could be a plus side to the sub-zero temperatures we’re experiencing this winter – the cold weather may well decrease the number of invasive pests we have. For example, the Hemlock Woolly Adelgid (the aphid-like introduced insect decimating the Eastern Hemlock population) succumbs at 4 or 5 degrees F. However, other insects aren’t phased by the cold until it dips way below zero. At -20 F., roughly half of the Emerald Ash Borer larvae (an invasive beetle that is highly destructive to ash trees) overwintering in trees will die. Once the temperature reaches -30 F., there’s a 90 percent mortality rate. Bed bugs face instant death at -22 degrees F., but it takes 24 hours to kill them at -11 degrees F. and 72 hours to kill them at 0 degrees F. Unfortunately, once an invasive insect establishes itself, even if its numbers go way down for whatever reason, it usually rebounds in several years’ time. Some invertebrates are not affected by the cold temperatures. The Black-legged (Deer) Ticks that reside on moose, deer, mice, birds and other hosts can withstand sub-zero temperatures as they have the warmth of their hosts’ bodies to keep them warm. In order for ticks to succumb to the cold, the frigid air has to last until May, when the fertilized female ticks fall off their hosts to lay their eggs.

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Snowflea Air Bags

12-23-13 snowflea IMG_0947Snowfleas are such remarkable little arthropods that they merit at least an annual post. The recent warm weather brought them up out of the leaf litter to the surface of the snow, where they constantly hurl themselves from one spot to another. If you don’t mind getting your knees wet, you can watch as snowfleas tuck their head down and catapult themselves through the air. Just before launching themselves, the snowflea everts three anal sacs from its anus. When the snowflea lands, these sticky appendages act like automobile air bags, absorbing the shock of landing as well as preventing the snowflea from bouncing around. There may be another function that they perform, but it is not known at this time what that might be. While there are many genera of snowfleas, only species in the genus Hypogastrura possess anal sacs.

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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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Blackberry Seed Gall

Galls, abnormal plants growths caused by many agents including insects, are formed during the growing season on the buds, leaves, roots and branches of plants as a response to chemicals or physical irritation. These galls serve as shelters and a source of food for their inhabitants. Blackberry is host to numerous gall-making insects, including mites, midges and gall wasps, and their temporary homes (galls) are more obvious now that Blackberries have lost their leaves. The Blackberry Seed Gall is caused by a cynipid gall wasp, Diastrophus cuscutaeformis. This wasp gets its species name from the resemblance of the galls it forms to the fruit of Dodder or Cuscuta, a parasitic plant. A cluster of small, globular, seed-like galls within which the gall wasp larvae live are pressed together in a lump surrounding the cane. Each of these 1/10th-inch diameter chambers bears a spine, and together they create a reddish-brown hairy mass.12-3-13 blackberry gall IMG_0555


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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Carpenter Ants Huddling

11-14-13 carpenter ants 028Insects that live in northern New England have different strategies for surviving the winter. Carpenter ants live in the center of both dead and living trees, in galleries that they have chewed throughout their nest. Although wood is a good insulator, it still freezes during the winter. The ants tend to cluster together and enter a state of slowed metabolism called diapause. In addition, carpenter ants also produce glycerol, a compound which acts as antifreeze preventing destructive ice crystals from forming in their bodies.

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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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Spreadwing Damselflies Mating & Laying Eggs

10-18-13 spreadwing damselflies 019Believe it or not, there are still damselflies (and dragonflies) that are flying, mating and laying eggs in the middle of October in northern New England. Certain damselflies known as “spreadwings,” unlike most other damselflies, perch with their wings partially open. (Another tell-tale spreadwing sign is that they often perch at roughly a 45 degree angle.) Spreadwings are weak flyers, and you usually see them flying low and for short distances. When sexually mature, the males tend to spend their days perched on vegetation along a pond’s shoreline. The females, like most dragonflies and damselflies, return to the water only when ready to breed. The pictured spreadwings (Spotted Spreadwings, Lestes congener, I believe) are one of the latest species of damselflies active in the fall; these two were resting before resuming egg-laying. The male (at top of photo) grasps the female’s “neck” (to prevent other males from replacing his sperm in her) while the female uses the sharp ovipositor at the end of her abdomen to slice into emergent vegetation and lay her eggs, which eventually end up in the water when the plants die.


Basking Bumblebees

10-10-13  basking bumblebee 016Bumblebees are some of the earliest bees to emerge in the spring and are often the last to be seen in the fall. They can regulate their own body temperature by shivering or basking in the sun. This enables bumblebees not only to stay active longer during the season, but also during wet or cooler weather. Look for them on sunny patches of ground at this time of year.

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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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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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Spider Spinnerets

9-30-13 black and yellow sp. spinnerets2 IMG_4897Responses to yesterday’s Mystery Photo ranged from immediate deletion by a reader (due to the unappealing nature of the photo), to guesses including “bee butt,” “caterpillar mouthparts” and “deer tick.” Most responders, however, guessed correctly – the photograph was of the spinnerets of a Black-and-Yellow Garden Spider, Argiope aurantia.

Most spiders have six spinnerets — organs located on their abdomens from which silk is extruded. The individual spinnerets move independently yet in a highly coordinated manner. Each spinneret is dotted with many tiny spigots, through which various types and thicknesses of silk are extruded. The strong muscles that move the spinnerets also force liquid silk through the narrow spigots. This pressure, as well as external pulling by the spider, rearranges the liquid silk molecules into a solid but flexible thread. Although spider web silk is only about one millionth of an inch thick, weight for weight, it is stronger than steel (but not as strong as Kevlar). Unlike in the Mystery Photo, the spinnerets in this photograph are extruded and in use.

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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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