Galium Sphinx Moth Larvae Pupating
Some of the largest moths in the world belong to the hawk, or sphinx, moth family. As larvae, most hawk moths have a “horn” at the end of their body. One of the most familiar hawk moth caterpillars is the Tobacco Hornworm, found on tomato plants. Most species produce several generations a summer, pupating underground and emerging after two or three weeks. One exception is the Galium Sphinx Moth (Hyles gallii) pictured, which usually has only one generation a year. In the fall the larvae, or caterpillars, work their way underground where they overwinter as pupae inside cocoons in a shallow burrow, emerging as adult moths next spring.
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Mourning Cloak Caterpillars Pupating
Having overwintered as an adult, the Mourning Cloak butterfly (Nymphalis antiopa) is one of the first butterflies seen in early spring. Mating takes place and eggs are laid in a cluster encircling a twig of a willow, cottonwood, elm, birch or hackberry tree. The hatching caterpillars stay together until they move off their host plant to pupate, which is what is happening right now and why you can find these distinctive spiny black and red caterpillars at this time of year. Adult Mourning Cloaks emerge in midsummer, enter a state of dormancy until fall and then seek a sheltered spot in which to hibernate until spring.
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Overwintering Moth Larvae Becoming Active
One of the last things one might expect to see on a newly-exposed grassy field in the middle of March is a caterpillar crawling along. This would be unexpected because most moths overwinter as eggs or pupae inside cocoons, not as caterpillars (larvae). Most moths, but not all. Some species of moths overwinter as larvae (and adults).
Tiger Moths (and Tussock Moths) overwinter as caterpillars and pupate in the spring before emerging as adults during the summer. One member of the Tiger Moth group that is familiar to many is the Isabella Tiger Moth, known as the Woolly Bear (Pyrrharctia isabella) in its larval stage. Another member of this group that overwinters as a caterpillar is the Great Tiger Moth (Arctia caja). As early as mid-March you can find both of these caterpillars wandering in search of a protected spot where they will form hairy cocoons that surround and protect their pupal cases. The pictured Tiger Moth adult (Great or Garden Tiger Moth) bears the white geometric stripes that give the members of this group their common name.
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White-blotched Heterocampa Caterpillars On The Move
It’s hard to believe, but this fuschia-colored caterpillar is going to emerge from its cocoon next spring as a relatively dull black and white moth called the White-blotched Heterocampa (Heterocampa umbrata). These caterpillars have two shiny knobs behind their head which are the remnants of “antlers” that the caterpillars have during their first instar. White-blotched Heterocampa larvae change color as they mature and develop. At any given stage, a caterpillar could be purple and fuchsia, or brown and tan or green and white; it is not unusual for them to be mistaken for three different species. The caterpillars can be found feeding on oak leaves. Look for the adult woodland moths at night, when they are attracted to lights. (Thanks to Lily Piper Brown who found two of these amazing caterpillars recently, and her mother, Sadie Brown, who photographed this one.)
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Second Generation of Brown-hooded Owlet Moth Caterpillars Active
In the Northeast, Brown-hooded Owlet moths (Cucullia convexipennis) produce two generations a summer. The larvae of the first generation mature in July, and the second generation matures from late August into October. Brown-hooded Owlet larvae are often found on aster and goldenrod plants, resting on stems (often head down) in plain sight during the day. First generation larvae feed on the leaves and the second generation consumes the flowers of these plants. (Photo: note molted skin above caterpillar.)
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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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Caterpillars Eating & Molting
The larval stage of a butterfly or moth is spent doing little but eating. Only as a caterpillar will these insects have chewing mouthparts, and they waste no time in using them. As they eat, caterpillars increase in size and their skin (exoskeleton) becomes tighter and tighter, as it doesn’t grow larger. The caterpillar grows a new, larger exoskeleton underneath the outer skin and then sheds, or molts, the old one. Most caterpillars molt five times. At first, the new exoskeleton is very soft and not very protective, but it soon hardens. The shed exoskeleton is often eaten before the caterpillar ingests more plant food.
There are names for the caterpillar’s stage of development in between each molt, called “instars.” When the caterpillar hatches from its egg, it is referred to as a “first instar” caterpillar. After its first molt, the caterpillar is referred to as a “second instar,” and so on up until the exoskeleton is shed for the final time, revealing the chrysalis (if it’s a butterfly).
The Monarch in the photograph is a very new 4th instar instar caterpillar (see antennae which haven’t hardened). It has shed three times. Its third exoskeleton (which it has just shed) is on the milkweed leaf behind the caterpillar. To see a real-time video of a Monarch molting go to https://www.youtube.com/watch?v=EbHyq3RwtxI.
(Thanks to Otis Brown for his keen eye in finding this Monarch caterpillar before it ate its just-molted skin. Also to Ba Rea ((www.basrelief.org) for her instar confirmation.)
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Black Swallowtail Larvae Defending Themselves
Caterpillars, the larval stage of moths and butterflies, are very susceptible to predators (escaping quickly is not an option). Much of their energy in this stage is devoted to defense mechanisms to thwart would-be predators. A partial list of these defenses includes irritating bristles with detachable tips (Tussock Moths), toxic “breath” (Tobacco Hornworms, consumers of tomato plants, tobacco and other plants in the nightshade family, release toxic, bad-smelling nicotine), toxic bodies (Monarchs) and anti-coagulant venom (Giant Silkworm Moths).
Black Swallowtail (Papilio polyxenes) larvae defense mechanism strategies change as they develop. In early stages, or instars, they mimic bird droppings (not an appealing meal for most predators) and older larvae possess bright yellow-orange, horn-like organs behind the head known as osmeteria (see photo inset). When threatened, larvae rear up, extrude the osmeterium, and attempt to smear potential predators with a chemical repellent.
Black Swallowtail larvae are frequently sought after by parasitoids, which can locate their hosts by chemicals in the hosts’ feces (frass). To decrease their chances of being parasitized, Black Swallowtail larvae toss their fecal pellets away from themselves with their mandibles.
To learn much more about both moth and butterfly larvae, go to http://www.thecaterpillarlab.org.
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Woolly Bears Seeking Hibernacula
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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Large Yellow Underwing Larvae Crawling On Snow
The 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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Gypsy Moth Caterpillar Explosion
The Gypsy Moth was introduced into the United States in 1869 by a French scientist living in Massachusetts. Since then its range has expanded to include the entire Northeast south to North Carolina and as far west as Minnesota and Iowa. The consequence of the introduction of this insect is staggering. According to the U.S. Dept. of Agriculture, since 1980, the Gypsy Moth has defoliated close to a million or more forested acres each year. In 1981, a record 12.9 million acres were defoliated. This is an area larger than Rhode Island, Massachusetts, and Connecticut combined.
The Gypsy Moth females lay their eggs, usually on host tree trunks, in late summer. The eggs overwinter and hatch in the spring. Gypsy Moth caterpillars feed on a variety of species of shrubs and trees, with White Oak being their preferred host, metamorphose, mate and repeat this process. Usually their numbers are not overwhelming, but due to the weather conditions we’ve been experiencing, the caterpillar population has skyrocketed in some areas, especially in southern New England.
Conditions were very dry in parts of New England in May 2014 and May 2015, which impeded the growth of a certain kind of Japanese fungus (Entomophaga maimaiga) that keeps the Gypsy Moth caterpillar population under control. Without this fungus present to keep their numbers in check, Gypsy Moths have flourished. Although there was some rain this spring, there were many areas that did not get enough to benefit the fungus, and in these areas, trees are now stripped of their leaves. It is possible in places in southern New England to track the pattern of rainfall simply by looking at where trees are still in full leaf. Fortunately, the time has come for Gypsy Moth caterpillars to pupate, so most of this year’s destruction has already occurred. Here’s hoping for a rainy May next year.
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Second Generation Calico Paint Moth Larvae Feeding & Resting
In the Northeast, Calico Paint Moths (Cucullia convexipennis), also called Brown-hooded Owlets, produce two generations a summer. The larvae of the first generation mature in July, and the second generation matures from late August into October. Calico Paint larvae are often found on aster and goldenrod plants, resting on stems (often head down) in plain sight during the day. First generation larvae feed on the leaves and the second generation consumes the flowers of these plants. The comparatively drab, brown adult moths they turn into can often be found on Wild Bergamot and Common Milkweed flowers in the early evening. (Thanks to Joan Waltermire for photo op.)
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Saddleback Caterpillars Preparing to Pupate
There is a group of moths (family Limacodidae) which are known as “slug caterpillar moths” due to the manner in which they travel during their larval stage, secreting a semi-fluid silk from their ventral pores as they move. These caterpillars come in all sizes and shapes. Among them is the Saddleback Caterpillar, which is much more colorful than the brown adult moth it eventually turns into. Saddleback Caterpillars are best known for their stinging (urticating) spines. Reputedly far worse than that of a bee, the sting of the Saddleback Caterpillar may be the most potent of any North American caterpillar. The larva’s bright colors serve to warn predators of its toxicity. Soon these caterpillars will be spinning cocoons (which can contain spines, as well) in which they will pupate until emerging as moths next spring. (Thanks to Rick Palumbo for photo op.)
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Milkweed Tussock Moth Caterpillars Feeding
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 and make them resemble little mops. When still fairly young, the siblings stay together, skeletonizing the leaves they consume, leaving only the strongest veins that contain sticky latex. As they mature, the caterpillars tend to wander, and it’s unusual to find large groups of them on a single leaf. At this point they often cut through a vein in order to prevent the latex from reaching the area of the leaf where they are feeding. (Older monarch caterpillars use this same tactic.) Like monarchs, milkweed tussock moths, because they’ve consumed the cardiac glycosides contained in milkweed and dogbane leaves, are toxic to predators.
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Fern Balls
At this time of year, many new sterile fern fronds have “fern balls” at their tips – something has taken the last few inches of the tip of the frond and stitched it together into a ball-shaped shelter bound with silk. If you open one of these balls, you may find frass – droppings from the immature insect that was dwelling within the ball while consuming the terminal leaflets of the fern. Sometimes, but not always, you’ll find the larva responsible for the frass. Many species of ferns, as well as other plants, are host to many species of larvae, and many of these larvae are immature moths. Pictured is Christmas Fern, Polystichum acrostichoides, which is likely the host of the larva of Herpetograma sphingealis, the Serpentine Webworm Moth, or its close relative, H. aeglealis. Larvae live in these shelters for about a month before pupating and emerging as small, brown moths.
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Eastern Tent Caterpillars Hatching & Building Tents
The adult Eastern Tent Caterpillar moth lays her eggs in late spring or early summer on a tree whose leaves its larvae will eat (black cherry and apple trees are favorites). Two to three hundred eggs are deposited in a mass that encircles a thin branch. Within three weeks fully formed caterpillars develop inside the eggs. The caterpillars remain there until the following spring, when they chew their way out of the eggs just as the buds of the host tree are starting to open. As soon as the caterpillars emerge, they construct a silk tent within which they reside, enlarging it as they grow in size.
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Cecropia Moths Pupating
Our 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
I 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
Black Swallowtail Larvae Soon to Form Chrysalises
In its younger days, this Black Swallowtail larva resembled a bird dropping, but in successive molts a green (or white), yellow and black pattern develops. Often discovered in vegetable gardens on carrot, parsley and dill plants, it also feeds on wild members of the carrot/parsley family (Apiaceae), including its favorite, Queen Anne’s Lace (pictured). Seeds as well as leaves are rapidly consumed, as the time for one last molt and the development of a chrysalis in which to overwinter approaches.
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The Give and Take of Food in a Paper Wasp Nest
Like 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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Abbott’s Sphinx Moth Larva
Abbott’s Sphinx Moth larvae feed on grape and Virginia creeper leaves during the night. During the day they tend to rest on the woody vines of the plants they are eating, and because they are well camouflaged, they remain hidden from most humans’ eyes. Both as larvae and adults, these moths are well equipped for survival. Older larvae have two color forms, one resembling unripe green grapes (in photo), and the other is brown and looks much like a branch. In their last stage, or instar, both forms have a rear eyespot which looks like a human eye, right down to the white reflection spot in it, which scares off potential predators. If the caterpillar is pinched or prodded, it squeaks and tries to bite the attacker. The adult moths, which emerge next summer after pupating all winter, also defend themselves with both color and behavior. They are brown with yellow bands on their underwings, which make them look something like a bumblebee, and when they fly, they create a buzzing noise. (Thanks to Heidi, Tom and Simmy Wetmore for photo op.)
Caterpillar Survival Strategies
The larvae of moths and butterflies are very susceptible to predation, especially by birds, and they utilize many different strategies to protect themselves. Shapes, colors and behavior all contribute to their survival. Some larvae take on the appearance of less appetizing things, such as bird droppings, twigs or leaves. Some have large eye spots which presumably scare predators. Others have cryptic coloration which makes them all but invisible. The pictured green caterpillar uses both color and behavior to visually disappear on the fern it is consuming.
White Admiral/Red-spotted Purple Caterpillars Emerge from Hibernation
Butterflies in the family Nymphalidae are also referred to as brush-footed butterflies (their front pair of legs are much reduced, brush-like and nonfunctional). Several species of Admiral butterflies belong to this family, and one of the most common in New England is the White Admiral, also known as the Red-spotted Purple. White Admirals overwinter as caterpillars and emerge in late April to feed for several weeks on the young leaves of cherries, willows, poplars and birches, as well as other trees, before forming chrysalises and transforming into butterflies. It is relatively easy to recognize the larva of any species of Admiral butterfly, as they are our only horned bird-dropping mimics. Quite an effective way to discourage predators!
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