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Moths

Polyphemus Moth Cocoon

Congratulations to Stein, the first person to correctly identify Monday’s Mystery Photo as the cocoon of a Polyphemus Moth!

The Polyphemus Moth is one of our giant silk moths, spinners of the largest cocoons in North America.  Leaves are often woven into the surface of the cocoon in which the Polyphemus pupa spends the winter.  Unlike most other giant silk moths’ cocoons, the Polyphemus Moth cocoon lacks an escape “valve” at one end. In order to emerge (as an adult) from the cocoon the summer after it spins it, the moth secretes an enzyme that digests and softens the silk at one end. Then it moves about the cocoon in a circular pattern, tearing the softened silk with two spurs located at the base of each wing on its abdomen. Eventually it escapes by splitting the silk and pushing the top up.

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American Dagger Moth Caterpillars Roaming

American Dagger Moth (Acronicta americana) caterpillars are present from June to October in the Northeast, but because of their size (up to 2 ½”) and their searching for a suitable site to pupate in over the winter, they are very evident right now.

American Dagger Moth caterpillars have lemon yellow (early instars) or white (late instars) setae, or hairs.  Their distinctive characteristic is the pattern of black tufts: two pairs of diverging tufts along the middle of the caterpillar and one thick black tuft at the end. As larvae they have a wide variety of host trees, including alders, ashes, birches, elms, hickories, maples, oaks, poplars, walnuts, and willows.

After locating a wintering site, these caterpillars will spin a cocoon in which they will spend the next several months as pupae.  Late next spring American Dagger Moths will emerge from their cocoons as two-inch-long brown moths.

If touched, these caterpillars can cause a mild allergic reaction (a rash) in some people who touch the them.

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Monkey Slug Season

Congratulations to Rinky Black, who was the first person to accurately identify the Mystery Photo as a Monkey Slug!

Some of our dullest-looking moths started their lives out as colorful, bizarrely-shaped caterpillars.  In particular, there is a family of caterpillars (Limacodidae) known as “slug caterpillars” which come in all kinds of unusual forms and colors.  They can be naked or densely hairy, and they usually have stinging hairs. The Hag Moth (Phobetron pithecium), found throughout eastern North America, is one such moth. Whereas the adult moth is a dull brown, the caterpillar stage is anything but dull.  Known as the Monkey Slug, the caterpillar stage of this moth has three pairs of long “arms” and three additional pairs about half as long.  Its appearance has been likened to a tarantula (many of our insectivorous birds winter in the tropics, where there are tarantulas (which the birds avoid), and therein lies the reason for the caterpillar to look like one).  Although most photographs make Monkey Slugs look large, they measure only about an inch in diameter. Adult moths bear a slight resemblance to bees and wasps.

What is eye-catching about Monkey Slugs (as well as other slug caterpillars), besides their bizarre appearance, is the way in which they move.  Monkey Slugs glide – instead of the typical prolegs (located behind six true legs) they have suckers (see bottom right inset).  This gliding is responsible for its being classified as a “slug” caterpillar, for it moves much like a slug does.  The Monkey Slug is one of the slug caterpillars that does not sting, so you can handle it safely should you find one. (Thanks to Kathy and Geoff Marchant for photo op.)

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Snowberry Clearwing Moths Gathering Nectar

There are four species of clearwing (also referred to as hummingbird) moths in North America. The most familiar ones are the Snowberry Clearwing (Hemaris diffinis) and the Hummingbird Clearwing (Hemaris thysbe).  These day-flying moths fly and move like hummingbirds (hovering near flowers while drinking nectar) and the males have a flared “tail” like that of a hovering hummingbird.  It is also very easy to mistake one for a bumble bee.  Scales cover the wings of butterflies and moths, but clearwing moths lose many of these scales and thus have partially transparent (“clear”) wings.

Like most moths, clearwing moths have a very long tongue (can be twice as long as their body) which they carry rolled under their heads and that they use to reach the nectar of long-necked flowers.  They are attracted to the flowers of phlox, beebalm, honeysuckle and swamp milkweed (pictured), among others. If you approach a clearwing moth as it hovers, you may detect the humming sound that they make with their wings.

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Great Ash Sphinx Moth

Sphinx moths are notable for their fast flight and rapid wingbeat.  These attributes account for one of their common names — “hawk” moth. Most species of sphinx moths are capable of hovering in front of the flower from which they are drinking nectar, and some species are referred to as “hummingbird” moths.

In their larval form, sphinx moths are notable for the horn which extends upward near the end of their abdomen.  Tomato growers are familiar with the Tobacco Hornworm (Tobacco Hawk Moth/Carolina Sphinx Moth) and Tomato Hornworm (Five-spotted Hawk Moth).

Less frequently encountered is the larva of the Great Ash Moth (Sphinx chersis). Named for a host plant of the adult moth, this greenish or pinkish caterpillar has seven long diagonal lines along its body, which are sometimes edged with pink. Its black spiracles (external openings that allow gas exchange) are elongate and ringed with white. Its horn is blue or pink.  As an adult moth, it is gray with black markings and has a wingspan of up to five inches. You’re most likely to see this moth at dusk, feeding at deep-throated flowers. (Thanks to Heidi Marcotte and Tom Wetmore for photo op.)

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Promethea Moth Cocoons

11-28-18 promethea moth cocoon_U1A2802

At this time of year, most deciduous trees have lost their leaves. Bare branches make looking for cocoons and finding them much easier. A single leaf dangling from an otherwise barren branch of a tree might very well turn out to be the winter domicile of a Promethea Moth (Callosamia promethea) pupa.

These giant silk moths construct their protective two-inch-long silken cocoons while still in their larval/caterpillar stage.  First silk is spun around the stem of the leaf (petiole) as well as where the petiole attaches to the branch, in order to reinforce the attachment of the leaf to the tree.  The cocoon is then spun, with the leaf serving as its outer covering. The result is a perfectly disguised shelter that looks like a dead leaf hanging from a branch.

The caterpillar pupates after completing the cocoon.  After spending the winter in the pupal stage, the adult moth will emerge in early summer through a valve-like opening at the upper end of the cocoon.

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Woolly Bears Seeking Hibernacula

10-10-18 isabella tiger moth 119

The Isabella Tiger Moth typically has two broods during the summer.  The caterpillars (Woolly Bears) in the first brood pupate and emerge as adult moths mid-summer.  The second brood overwinters as caterpillars and pupate in the spring.  The Woolly Bears we see crossing roads at this time of year are second-brood caterpillars in search of protective hibernation sites (hibernacula).

Old-timers predicted the severity of the coming winter by the relative lengths of the black and brown bands of the caterpillars when they became easy to observe in the fall – the longer the black sections and narrower the brown section, the harder a winter they were in for.  In fact, this may have had some validity, as brown hairs (setae) are added to the middle band every time the caterpillar molts. Therefore, the older the caterpillar, the wider the brown band.  If winter comes early, the caterpillar’s brown band would be relatively narrow due to the fact it didn’t have time to mature fully and develop a wider brown section before hibernating.

The adult stage of the Isabella Tiger Moth is often overlooked, due to the appeal of the larval stage.  This tan moth, with a wingspan of 1 ½ – 2 inches, has tiny black markings on its wings.  Male and female are sexually dimorphic and can be distinguished by the color of their hind wings.  Males have yellow-pale orange hind wings while the hind wings of females are rosy. (Photo:  Woolly Bear; photo inset: female Isabella Tiger Moth)

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Fall Webworms

9-10-18 fall webworm nest_U1A9376

For several weeks white webs on the tips of branches have been apparent on many trees.  These silken tents are the work of the Fall Webworm (Hyphantria cunea), a moth most associated with its larval stage. Fall Webworm caterpillars construct a web over the end of a branch, enclosing leaves on which they feed.  As the hairy, white caterpillars grow, they enlarge the web to encompass more leaves, with tents sometimes extending two to three feet.

Often mistaken as the work of Eastern Tent Caterpillars, the tents of these two moths can be distinguished by the season they appear (ETC are active in the spring, Fall Webworms in the fall) as well as the location of the tents (ETC are usually in the crotches of trees, Fall Webworms at the tip of branches). As soon as the eggs hatch in early summer, the Fall Webworm larvae begin to spin small silk webs over the foliage of the deciduous trees on which they feed (over 90 species). By fall the tents are conspicuous. A look inside one  reveals caterpillars, dead partially-eaten leaves, and fecal droppings.

The larvae feed together inside the increasingly large web for roughly six weeks, at which point they often start feeding independently before pupating in the ground over the winter and emerging as adult white moths the following summer.

If your favorite tree has one or more Fall Webworm nests in it, there’s no cause for alarm. These caterpillars may defoliate a tree occasionally, but rarely kill it, and usually only build tents on a handful of branches, if that. The larvae have more than 50 natural predators and 36 parasites that help control them. Also bear in mind that Fall Webworms do not eat the buds of next year’s leaves and the leaves they are feeding on will soon to drop to the ground. Next year leaves will appear on the currently affected branches with no sign of last year’s damage.

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Second Brood of Snowberry Clearwing Moths In Flight

8-22-18 snowberry clearwing moth_U1A6071

Clearwing moths are strong and fast fliers with a rapid wingbeat, like the other members of the Sphingidae family. Most species in the group are active at dusk and feed much like hummingbirds, hovering in front of a flower and sipping nectar through their extended proboscis.  In most species, the larval stage is called a “hornworm” because the caterpillar’s posterior end has a horn-like appendage protruding upward.

Like its close relative, the Hummingbird Clearwing (Hemaris thysbe), the Snowberry Clearwing (Hemaris diffinis) is a day-flying moth, has transparent wings and is a mimic.  While they both hover at flowers, the Hummingbird Clearwing is said to mimic a hummingbird, while the Snowberry Clearwing is considered a bumblebee mimic.  To distinguish these two clearwings, if it has black legs and a black band that crosses the eye and travels down the side of the thorax, it’s a Snowberry Clearwing.

In addition to thistle, adult Snowberry Clearwings feed on honeysuckles, snowberry, hawkweed, lilacs and Canada violets. (Thanks to Barbara and Knox Johnson for photo op.)

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Abbott’s Sphinx Moth Larvae Maturing

7-23-18 Abbott's sphinx moth_U1A2632The larvae of sphinx moths, commonly called hawk or hummingbird moths, are easily recognized by the horn, eye spot or hardened button that is near the tip of their abdomen.  Most readers are probably familiar with the larval stage of tobacco and tomato hornworms (Carolina Sphinx Moth and Five-spotted Hawk Moth, respectively) which are found on tomato plants. A less observed sphinx moth, Abbott’s Sphinx Moth (Sphecodina abbottii), can be found on grape and Virginia creeper vines.  As a larva it molts several times and assumes three different appearances by the time it pupates.

Abbott Sphinx Moth larvae start out green, with a horn near the tip of their abdomen, like most other sphinx moths. However, when they are about half-grown, they turn blue-green and the horn develops into an orange knob (see inset).  In the last stages before they pupate, the larvae molt and the knob turns into an “eye,” complete with a black pupil and encircling iris.  The finishing touch is a white reflection spot that makes the eye appear moist and shiny.  At this point, the larvae may be either brown with a “wood-grain” pattern (resembling grape vines, a host plant) or brown with ten pale green saddles along the back (thought to resemble grapes).  Pictured are the second and third stages of a brown “wood-grain” Abbot’s Sphinx Moth larva.

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Polyphemus Moth Cocoons

12-15-17 polyphemus cocoon2 IMG_4455The Polyphemus Moth is a giant silk moth, a member of the Saturniidae family which includes some of the largest species of moths. Giant silk moths derive their name from both their size as well as the fine silk they use to spin the cocoons which serve as protection for the pupal stage in their life cycle.

Most Polyphemus Moth cocoons start out attached to a tree branch, although some are spun among leaves or grasses on the ground (see pictured cocoon). They are oval, roughly 1 ½” long and nearly an inch wide. Cocoons in trees are susceptible to attack by squirrels and woodpeckers, whereas mice are the biggest threat to cocoons on the ground.

The moth overwinters as a pupa inside the cocoon. Unlike most other giant silk moths’ cocoons, the Polyphemus Moth cocoon lacks an escape “valve” at one end. In order to emerge (as an adult) from the cocoon the summer after it spins it, the moth secretes an enzyme that digests and softens the silk at one end. Then it moves about the cocoon in a circular pattern, tearing the softened silk with two spurs located at the base of each wing on its abdomen. Eventually it escapes  by splitting the silk and pushing the top up.


Bruce Spanworm Moths Emerging

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If you’ve walked in northern New England woods recently, chances are great that you’ve noticed light tan moths with a one-inch wing span flitting about — with temperatures in the 20’s, this seems slightly incongruous. However, there are some insects that are active in cool weather, among them the Bruce Spanworm Moth (Operophtera bruceata), also called Winter Moth and Hunter Moth (these moths are active during deer hunting season, which approaches winter). The adults of this species are active from October to December.

Bruce Spanworm Moths belong to the Geometer family, the second largest family of moths in North America. All the flying moths you see are males seeking wingless, and therefore flightless, females to mate with. The females crawl up the trunk or branch of a tree and send out pheromones to attract winged males. After mating, the female lays her eggs which hatch in the spring. Larvae pupate in the summer and adult moths emerge in the fall.

Many Geometers are considered agricultural and forest pests. Bruce Spanworm larvae periodically defoliate hardwood trees, preferring the buds and leaves of Sugar Maple, American Beech and Trembling Aspen trees. In 1958 in Alberta, Canada, at the peak of a 10-year infestation, over 50,000 acres were moderately or heavily affected by Bruce Spanworm larvae.


Newborn Milkweed Tussock Moth Larvae A Bonanza For Predatory Stink Bugs

8-7-17 milkweed tussock moth larvae, first instar and (3) (003)Monarch larvae aren’t the only insects equipped to feed on the toxic cardiac glycoside-filled leaves of milkweed. Milkweed Tussock Moth larvae also dine on them, avoiding veins due to the latex-like, sticky white sap that could glue them in place. When they first hatch, Milkweed Tussock Moth larvae tend to stick together in “herds,” all feeding on the underside of the same leaf. This behavior provides a gold mine for predators such as predatory stink bugs (pictured) that discover them. Unlike their (plant) sap-sucking stink bug relatives, predatory stink bugs feed on more than 100 species of insect pests, often attacking insects much larger than themselves, drinking their body fluids with their needle-like beak. (Photo taken and kindly donated by Chris Doyle)

 

 


Blinded Sphinx Moth vs. One-eyed Sphinx Moth

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Moths in the family Sphingidae are commonly called “hummingbird” (for their habit of hovering as they feed on nectar from flowers), “sphinx” (the larva holds its legs off the surface and tucks its head underneath, resembling the Egyptian Sphinx) or “hawk” (they fly with great speed and precision) moths.   Most are fairly large, with some species having a wingspread of up to 5” or more.

One group of sphinx moths is referred to as the “Eyed Sphinx Moths,” two of which are the Blinded Sphinx Moth (Paonias excaecata) and the One-eyed Sphinx Moth (Smerinthus cerisyi). The derivation of their respective common names can be easily ascertained by examining the upper surface of their hind wings. The Blinded Sphinx Moth has a single blue eyespot on each hindwing, whereas the One-eyed Sphinx Moth has a round or diamond-shaped black spot (“pupil”) in the center of each blue eyespot. The Blinded Sphinx Moth is light brown, whereas the One-eyed is a violet-gray. Both moths have scalloped wings that are held elevated and slightly away from the body. They are nocturnal, and regularly visit lights in small numbers. Their life is short, and adults of both species do not feed.

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Luna Moths’ Sonar Scramblers

6-26-17 luna moth 001Luna Moths, Actias luna, are known for their hindwings’ beautiful, long, green tails. These tails are not simply decorative, nor is their primary function to attract a mate (pheromones do that). A recent study found that Big Brown Bats have an easier time catching Luna Moths that have lost their tails. Further research revealed that Luna Moths defend themselves from voracious bats patrolling the night air by spinning the tips of their two wing tails in circles. The twisting tails of the moth act like a sonar shield, interfering with the bat’s means of locating them – echolocation. In contrast with the stronger, ever-changing echoes coming off of the moths’ large flapping wings, the twisted shape of the tails create a persistent weak echo signal. According to researchers, this could make the insects trickier to catch, and harder to track as they fly.

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Modest Sphinx Common & Scientific Name Correction

6-16-17 moest sphinx IMG_8668Poplar Hawk-moth and Big Poplar Sphinx are both common names used for more than one species of moth. Normally, the scientific name would clarify the identity of a species, but in yesterday’s post, the scientific name given was that of another moth with the same common name.

The confusion over the use of the same common names for different species of moths has led to the current use of the name Modest Sphinx for the moth depicted in yesterday’s post, with a scientific name of Pachysphinx modesta. It derived both common and scientific names from the fact that when it is seen up against a tree or other substrate with its forewings not fully extended, the bottom half of the moth is dark, as though “modestly covered” by a cloak or shawl. Thank you, Andree Sanborn, for your sharp eyes!

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Poplar Hawk-moths Emerging, Mating & Laying Eggs

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June is well-known for the giant silk moths that emerge this month, but there are other large moths that are encountered as well, one of which is the Poplar Hawk-moth (Laothoe populi). Hawk-moths, also known as Hornworms (their larvae, which feed mainly on species of poplar, usually have a horn), are a type of Sphinx moth, which are known for their fast, enduring flight. One of the more familiar species of this family is the day-flying Hummingbird Hawk-moth, which can be seen hovering at flowers while sipping nectar with its proboscis.

Adult Poplar Hawk-moths, with wingspans as large as four inches, emerge in early summer. Their life is so short that they do not have a functional proboscis and do not eat, but concentrate on mating. Females extend a scent gland from the end of their abdomen to lure in the night flying males whose large claspers are frequently wide open as they fly in to lights around midnight. The moths mate and the females lay their pale green eggs on the leaves of poplars and willows, which the larvae eat once they hatch. Fully-grown caterpillars pupate and overwinter in shallow burrows in the ground.

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Large Yellow Underwing Larvae Crawling On Snow

12-12-16-large-yellow-underwing049a2252The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth known as the Large Yellow Underwing (Noctua pronuba). Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar. The Large Yellow Underwing larva is one of many species  known as cutworms that feed on herbaceous plants. Introduced from Europe to Nova Scotia in 1979, this species has since spread north to the Arctic Ocean, west to the Pacific, and south to the Gulf of Mexico.

Larvae sporadically feed through the winter months whenever temperatures are above the mid-40s. The Large Yellow Underwing larva has been nicknamed the winter cutworm and the snow cut-worm for its ability to feed actively when other cutworms are dormant for the winter. Occasionally on warmer winter days, such as we had last week, you see them crawling on the snow.

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Milkweed Tussock Moths

9-6-16  milkweed tussock moth larvae 20160830_1764Milkweed Tussock Moth caterpillars are responsible for eating all portions of milkweed leaves but the largest veins that contain sticky latex. They can tolerate the cardiac glycosides within the milkweed plant that are toxic to most other insects as well as certain mammals and birds. Like Monarchs, these caterpillars retain the toxic compounds as adults, and are therefore avoided by many predators.

Female Milkweed Tussock Moths lay their eggs in masses on the underside of milkweed and dogbane leaves, which their larvae will eat. The hatching caterpillars are gray and hairy, but in no time they have developed the tufts of hairs that give them their name. When fairly young, the larvae tend to stay together, skeletonizing the leaves they consume. As they mature, the caterpillars tend to wander, and it’s unusual to find large groups of them on a single leaf.

Many of the insects that feed on milkweed have orange and black patterns as both larvae and adults. These colors serve as a warning to would-be predators. One of the adult Milkweed Tussock Moth’s main predators is bats. While the moth possesses these colors during its larval stage, as a pale brown adult (the stage that nocturnal bats prey on them) it lacks the bright coloration (which would provide little protection in the dark) but has an organ that emits an ultrasonic signal easily detected by bats. The signal warns that an attack will be rewarded with a toxic and distasteful meal, thereby deterring predation.

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Luna Moths Emerging

6-27-16  luna moth 002June is giant silk moth month, when these giant-bodied/winged moths in the family Saturniidae emerge.  Perhaps the most familiar giant silk moth is the Luna Moth, Actias luna. One of the largest moths in North America, its wingspan measures 4 ½ inches.  If you see one of these beautiful creatures, you are witness to its very short adult  lifespan.  After emerging from their cocoons, Luna Moths live for only about a week, during which time their sole mission is to mate. Like many other ephemeral insects, adult Luna Moths have no mouthparts and thus, do not eat.

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Rosy Maple Moths Emerging, Mating & Laying Eggs

6-13-16  rosy maple moth 059Rosy Maple Moths (Dryocampa rubicunda) are easy to recognize, with their pink and yellow woolly bodies, pink legs and pink antennae.  Many adults are emerging from their pupal cases now, having spent the winter underground as pupae. Once metamorphosis is complete, the adult moths lose no time in finding mates and laying eggs, not stopping to even eat.  These members of the family Saturniidae are most active during the first third of the night, reducing their body temperature and activity in the morning and afternoon.

Mating takes place at night on the underside of a leaf, and 24 hours later the female lays clusters of 10-30 eggs (a total of 150 – 200 eggs) on the underside of the leaves of the larvae’s host plants, most often maples and oaks.  When the eggs hatch, the larvae usually remain on the same tree throughout their larval stage.

Known as Green-striped Mapleworms, the larvae initially feed together, but become independent feeders as they age.  Mapleworms change color as they develop.  When young, most have black heads and yellow bodies, but with age their heads turns reddish-brown and their bodies assume a shade of green.

In New England there is only one brood per summer; further south, there are multiple broods.

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Promethea Pupae Parasitized

12-21-15 promethea cocoon 257Although a lack of snow makes tracks difficult to find, there are other, more permanent, animal signs such as bird nests and cocoons that are visible this time of year. Among the more obvious is the cocoon of the Promethea Moth – a giant silk moth. When the time for pupating arrives the Promethea caterpillar selects a leaf and strengthens its attachment to the tree by spinning silk around the petiole of the leaf as well as the branch it grows on (to assure that it doesn’t fall off the tree). With more silk it rolls the leaf up into a tube and then proceeds to spin its cocoon inside the rolled-up leaf, leaving a valve-like structure at the top of the cocoon through which the adult moth exits in the spring.

Unfortunately for silk moths, many are parasitized by flies and wasps (there are nearly 100 natural parasites that affect the 24 species of silk moths east of the Mississippi River). Frequently flies or wasps lay their eggs in silk moth caterpillars and then develop inside them. Eventually the fly or wasp larva secretes a substance that causes the caterpillar to pupate, at which time the fly or wasp also pupates and then exits the moth pupa and cocoon (see exit hole in smaller photo), causing the death of the moth pupa. Silk moth populations are decreasing, in part as a result of these parasitoids. Among others, a non-native parasitic tachinid fly, Compsilura concinnata, is wreaking havoc on silk moths.

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Snowberry Clearwing Larvae Pupating

snowberry clearwing larvae 125The Snowberry Clearwing (Hemaris diffinis), a type of Sphinx moth, is one of several daytime-flying “hummingbird moths,” so-called because of their ability to hover while drinking nectar from a flower, and because of the humming sound they make, much like a hummingbird. The yellow and black bands of the Snowberry Clearwing’s abdomen also cause it to be mistaken for a bumblebee. The most distinctive thing about this moth is that a large portion of its wings are transparent, due to scales falling off.

Snowberry Clearwings are often seen around the time that beebalm is in bloom, in July and August. The females entice the males with a pheromone that they produce from glands at the tip of their abdomen. After mating, the females lay their tiny, round, green eggs on their larval food plants. Like many Sphinx moths, the larvae have “horns” at the end of their bodies. Most Snowberry Clearwing larvae are green, but they can be brown, as well. Both colors enable them to be well camouflaged as they feed on the leaves of honeysuckle, viburnum, hawthorn, snowberry, cherry, mint, and plum. The caterpillars are active until late fall, when they drop to the ground, spin a loose cocoon and pupate, partially protected by leaf litter. The pupa spends the winter hidden under the leaves, and the adult moth emerges the following spring. (Thanks to Tom Wetmore and Heidi Marcotte for photo opportunity.)

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Leaf Miners

9-29 leaf miners IMG_6836A leaf miner is the larval stage of an insect (primarily moths, sawflies and flies) that feeds on leaf plant tissue. Most of these insects feed for their entire larval period within the leaf, creating tunnels between the upper and lower leaf surfaces. Some will pupate within the leaf mine, while others cut their way out when they are full-grown and pupate in the soil.

The pattern of feeding tunnels, as well as the pattern of droppings, or frass, within them (darker sections of tunnels), combined with the species of plant on which they occur, can sometimes identify the species of insect that created the mines. A moth larva, the Common Aspen Leaf Miner (Phyllocnistis populiella), leaves delicate, serpentine mines (see photo) that are diagnostic of this species.

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