September 6, 2023 by Beth

Beyond Monarchs and Viceroys

Great-spangled fritillaries sport a checkerboard pattern on their dorsal wings. A creamy yellow band separates silvery spots or “spangles” on the ventral surfaces.

In late summer, chances are good that you’ll notice lots of orange-and-black butterflies in gardens, meadows or roadside areas. But, not every one that you see is a monarch, or its look-alike, the viceroy. Fritillaries, another group of large orange-and-black butterflies, are on the wing into September in the Upper Midwest, favoring open sunny gardens, grasslands, and meadows.

Fritillary comes from the Latin word “fritillus,” which means checkerboard or dice — and most butterflies in this family sport a checkered design on their wings. Of Minnesota’s 12 fritillary species, the most widespread are the great-spangled, Aphrodite, Atlantic, silver-bordered, meadow and variegated.

I’ve spotted great-spangled fritillaries (Speyeria cybele) in our garden and along country roads where I’ve recently walked. The largest of Minnesota’s fritillaries, with a wingspan of 2.5-to-4.0 inches, great-spangled adults display an orange, brown and black pattern of stripes, dots and bars on their upper wings. The undersides of the hindwings shimmer with two rows of large silver spots (referred to as spangles) separated by a wide, creamy yellow band not seen in other fritillaries.

Faded colors and worn, jagged-edged wings indicate an elderly great-spangled fritillary nectaring on this thistle.

In June, great-spangled males appear first, followed by females about a month later. Females lay eggs in late summer and fall, placing them singly, on or near the base of common violet species (viola) — violets alone are the host plant for their larvae. The caterpillars hatch in the autumn, but stay hidden in leaf litter until the following spring when violets are freshly growing. Caterpillar s are black with reddish-orange knobs that give rise to black spines. They are secretive and only feed at night.

Great-spangled fritillary caterpillars, and many other fritillary larvae, feed only on violet (viola) species.

Unlike their violet-dependent larvae, adult fritillaries nectar on many different flower species, including milkweed, clover, black-eyed Susan’s, vetches, thistles, Joe-Pye, monarda, members of the mint family, dogbane and many types of coneflowers. Fritillaries are preyed upon (especially the caterpillars) by dragonflies, paper wasps and other large insects, spiders and birds.

What can you do to help these beautiful pollinators? If you have violets in your garden, don’t weed them all out. Without violets, there would be no fritillaries! Leave a few in your garden or yard year-round for great-spangled and other types of fritillary caterpillars to eat.

Most common in eastern North America, great-spangled fritillaries range from British Columbia across southern Canada and the northern United States to the Atlantic, south to central California, northern New Mexico and northern Georgia.

Leave a few violets tucked into your garden so that fritillaries can lay their eggs on them in the fall. Caterpillars will feed on them in the spring.

Sources and Further Reading

Butterflies and Moths of North America

North American Butterfly Association

University of Kentucky Entomology

Weber, Larry. (2006). Butterflies of the North Woods. Duluth, Minnesota: Kollath & Stensaas Publishing

June 28, 2023 by Beth

More Than a Weed

I’ve battled bishop’s weed (Aegopodium podagraria) in my garden for 35 years.¹ As much as I detest it, (please don’t plant it), I’ve learned that what’s despised by one creature may mean survival to another. Bishop’s weed, a member of the parsley family, is one of a small number of host plants or “homes” for native black swallowtail butterfly caterpillars.²

A black swallowtail caterpillar (Papilio polyxenes) feasts on bishop’s weed, a member of the parsley family.

As I dug out the weeds a couple of weeks ago, I spotted a caterpillar with light blue-green and black stripes dotted with yellow. The clues to its identity were its location on a member of the parsley family, the only plant type that black swallowtails live on and eat, and the color and pattern of its stripes. (It looked similar to a monarch, but monarch caterpillars only eat milkweed and their stripes are yellow, black and white.) I searched through the rest of the bishop’s weed and found a second caterpillar. In May I’d seen an adult black swallowtail visiting the weed, where it must have deposited eggs.

Two rows of well-defined yellow spots help to distinguish the black swallowtail from other swallowtail species in our area.

Not a rare butterfly, but a handsome one, the black swallowtail (sometimes called the parsley swallowtail) is native to the eastern United States and Canada. Its body and wings are black with highlights of yellow, blue and orange. The tail ends in two narrow lobes that give it the common name of swallowtail. Two rows of bright yellow spots mark the wings. The hindwings are blue in the area between the yellow rows near the tail. Each hindwing ends in a circular reddish spot. The underside of each wing has rows of light yellow spots, with bands of orange separated by spatterings of blue. Females usually show more blue coloring and males usually have more yellow. The wing span is 3.5 – 4.5 inches, with the female generally larger than the male.

The undersides of the hindwings are marked with bright orange and a dusting of blue.

In the Upper Midwest, black swallowtails produce two generations of offspring between May and October. The second generation overwinters in a brown chrysalis until the following spring. The caterpillars in my garden probably hatched in May. Depending on weather conditions and host plant availability, the eggs hatch in three-to-nine days. The caterpillars eat and grow through five stages, or instars, as they increase in size and change in appearance, which may take up to 30 days. The mature caterpillar forms its chrysalis and molts one final time. The ones I saw will leave their chrysalises in two-to-three weeks as mature black swallowtails ready to produce the next generation. Adults nectar on clover, milkweed, thistle, bee balm and other perennials. Watch for them to be on the wing in July — and, consider growing one of the more well-behaved members of the parsley family, such as dill, carrot, parsley or sweet fennel, on which this lovely creature can live and dine!

¹Also known as goutweed and ground elder, this non-native member of the parsley family was imported and marketed as a fast-growing ground cover that was frequently planted with European buckthorn (Rhombus cathartica) and creeping bellflower (Campanula rapunculoides). There’s also a variegated form called snow-on-the-mountain. Over the years, we’ve had it chemically treated, dug out and the soil replaced, but it returned each time. Now, I just try to prevent it from spreading.

²Other members of the parsley family include carrot, dill, sweet fennel, Queen Anne’s lace and, of course, parsley.

Green Darner Migration

Common green darner female (Anax junius)

On a windy, warm September evening, the sun has set; the air is soft and dusky. Migration is underway, but not the avian sort. A few large common green darner dragonflies zigzag beneath the trees hawking insects. I look skyward and far above me, a river of swarming green darners surges — hundreds of them — straight south ahead of a cold front.

Born in Minnesota, these green darners migrate to the Gulf Coast of the southern United States and Mexico. When they arrive, they’ll mate and lay eggs to produce the next generation, which will migrate north in April or May. When they arrive here, they will mate and give rise to a new generation before dying. These progeny will hatch by late August and continue the cycle of migration and reproduction.

But that’s not the entire story! Common green darners are present in the north all summer — so where did they come from? There’s a resident population that doesn’t migrate. They’re active and deposit eggs throughout the summer and autumn. However, their young, called naiads, won’t mature until the following spring. They will wait out the winter on the bottom of a pond, marsh or slow-moving river or stream.

Averaging 3 inches in length, and with a wingspan of 3.5 inches, green darners are among our largest dragonflies. This one also is a female. Males’ abdomens are bright blue.

Green darner adults eat mosquitoes, midges and other flying insects. The aquatic naiads feast on mosquito larvae and other aquatic insects, tadpoles and tiny fish. Green darners are eaten by spiders, large robber flies and birds such as kestrels.

Further Reading

Mead, Kurt. (2009). Dragonflies of the North Woods. Duluth, Minnesota: Kollath & Stensaas Publishing.

Smithsonian Magazine

UW-Milwaukee Field Station

August 20, 2022 by Beth

Hidden Music Maker

*Katydids’ green bodies are easily mistaken for plant leaves. Can you spot one under the flower on the right?*

Walk outside and listen on a late-summer or early autumn evening. Insect music has replaced the chorus of robins, mourning doves, northern cardinals and other birds. The new songsters might include tree and field crickets, cicadas, grasshoppers and katydids.

Unlike their more somber-colored cricket cousins, katydids are often bright green and are well camouflaged by plant leaves and stems. Very long antennae and wings held vertically over the body distinguish them from grasshoppers. Many could pass for a small leaf on a plant! I often hear katydids calling, but rarely see them.

Similar to their cricket kin, katydids create sound by rapidly moving the sharp edge of one wing against a ridge of bumps on the other wing — this is called stridulation. Each species creates a different sound. Most produce clicks, rattles or buzzes that differ in pitch, pattern and volume. Only one species, the common true katydid (Pterophylla camellifolia) “says” its name. (The link includes both group and individual recordings.)

*Katydids’ ears are located below the knee joint. Zoom in to see the small, dark oval shapes called tympanum.*

Katydids have narrow hearing organs located below each knee on their front legs. Though the location differs from mammalian ears, the ear structure is similar to our own. Simply put, sound waves cause a katydid’s eardrums to vibrate. The vibrations rock a small plate that transmits sound waves to the auditory vesicle, which contains fluid. The waves move through the fluid over tiny sensory cells that glean information and send electrical impulses to the katydid’s brain. Scientists theorize that locating a mate and avoiding predators are two key purposes of katydid hearing.

What eats katydids? Owls, kestrels, other birds, rodents, tree frogs, insects and spiders prey on them. Mainly vegetarians, katydids eat leaves and flowers of plants, but sometimes eat insects — including other katydids!

Next time you’re outside in the evening, listen for katydid calls. Crickets aren’t the only nighttime musicians!

Further Reading

Katydids – Wisconsin Horticulture

Katydids – Tettigoniidae

Songs of Insects

July 15, 2022 by Beth

Only This Moment

White-tailed doe (Odocoileus virginianus)

The eyes of a white-tailed deer are liquid and deep. Walking at a nature preserve, I sense and then spot a doe’s motionless face gazing at me from a dry creek bed. We stand alert and silent. Though I don’t see them, a young fawn or two are probably hidden nearby waiting for their mother’s signal to move. Birdsong, the wind and children’s voices in the distance fade away behind the curtain of green foliage. There is only this place and moment.

June 30, 2022 by Beth

Skimmer Dragonflies

Male widow skimmers (*Libellula luctuosa*) are dark brown with a bluish frost called pruinose.

What do you think of when you hear the term skimmer? A shore bird, a kitchen utensil, or perhaps a type of shoe? Skimmer also refers to the earth’s largest family of dragonflies, Libellulidae.

Skimmers might be the image that many envision when they “think dragonfly.” Skimmers’ wings are large and patterned with spots — usually black and a powdery grayish-white. Like all dragonflies, skimmers hold their wings spread out horizontally from the body when resting. The head is large with eyes that contact each other on top. Two inches is a common body length, but it can vary between one and three inches. Adult skimmers dine on many soft-bodied insects, especially mosquitoes, flies, small moths and winged ants. Nymphs, or immature dragonflies, develop underwater where they eat mosquito larvae, fly larvae and other aquatic organisms. Skimmers are preyed upon by raccoons, skunks, shrews, bats, turtles, snakes, frogs, fish, spiders, larger insects such as praying mantids, and many bird species.

A female twelve-spotted skimmer (*Libellula pulchella*) perches on a dead forb in an urban oak savanna.

The twelve-spotted skimmer (Libellula pulchella) and the widow skimmer (Libellula luctuosa) are two common skimmers of Minnesota. Though similar in appearance and size (about two inches long), the difference is in their wing spots. Male twelve-spots carry 12 black patches and eight white spots between the black ones. Male widow skimmers show a dark black wing patch from the wing’s base to about midwing. One large white spot extends outward from the black patch. Female and young juvenile males of both species only exhibit black patches. Males and females of both species are coppery brown, but adult males develop a whitish-blue dusty or frosted appearance, called pruinose, on the abdomen. Both species sport bright, neatly etched side stripes — yellow in twelve-spots and orangish in widow skimmers. In addition, the thoraxes of mature twelve-spotted skimmers display two yellow stripes.

Why the name widow skimmer? One explanation is that most male dragonflies carefully guard their mates during egg-laying, but widow skimmer females deposit their eggs unguarded, and thus became commonly known as widows. Another is that the black wing patches were thought to be reminiscent of a widow’s shawl.

A female widow skimmer’s wings show the black pattern reminiscent of a widow’s shawl.

Both skimmer species may be found near ponds, lakes and marshes, but they also venture away from water into fields and meadows. I observed two twelve-spotted skimmers in a small area of oak savanna in Saint Paul, about three city blocks away from a pond. One perched on a dead tree limb, the other atop a dried up forb, wings spread horizontally and glistening in the sun.

Though not the most eye-catching of dragonflies, I like them; they’re easy to observe because they often forage in open areas away from water and remain close to their conspicuous perches. Both species share a similar geographic area. Twelve-spots range throughout most of southern Canada, the continental United States and northern Mexico. Widow skimmers occur in southern Manitoba, Ontario, Quebec and Nova Scotia, across the United States, except for the Rocky Mountain region, and in a portion of northern Mexico. Both skimmer species are on the wing during the summer months and the twelve-spotted skimmer is active through September.

Further Reading

Minnesota Dragonfly: Twelve-spotted Skimmer

Minnesota Dragonfly: Widow Skimmer

September 13, 2021 by Beth

Gray Tree Frogs

Like tiny amphibious chameleons, gray tree frogs (Hyla versicolor) change color to match their surroundings. Sometimes bark-like gray or brown, at times a leafy green, and at others a mottled combination of color that mimics lichens or rocks, these tiny frogs elude predators through camouflage. Sometimes they even display a shade of creamy white or tan. No matter what color they exhibit, all gray tree frogs have bright yellow or orange marks under their thighs.

Why are they “tree” frogs rather than just frogs? All species known as tree frogs (or treefrogs) have large toe pads that enable them to climb trees, sides of buildings, and other structures. Climbing trees is all about catching the wide variety of food available there on warm summer nights: small insects and their larvae, spiders, mites, aphids, snails and even smaller frogs. At night gray tree frogs also climb sides of houses to perch on windows and capture small moths and other insects attracted to light. Because gray tree frogs are nocturnal, I often hear rather than see them unless they perch on the windows. What preys on them? Small mammals such as skunks, raccoons and opossums. Snakes, birds and larger frogs also eat them.

*Artificial lights attract gray tree frogs in search of insects. This little one climbed* *the side of the house.*

Gray tree frogs typically inhabit woodland edges and gardens near water. We’ve seen them at our cabin in rural Minnesota, and my sister, who lives in a Twin Cities suburb, has regulars that hang out in her garden. They pop up in damp places — the cat’s water dish, inside her garden watering can, under flower pots, on the patio furniture and in her small fountain. Adults are typically found higher up in trees or shrubs, while younger tree frogs are more terrestrial.

*This tree frog’s golden color blends well with the potted plant.*

*Gray and charcoal hues help camouflage a tree frog on this weathered deck.*

Unlike most frogs, the gray tree frog sounds more like a bird as it trills its one-note call. They breed from April to July and call most frequently during May and June, though it can be as early as April and as late as September. Females lay their eggs near a shallow pond or pool of water. Hatching and development takes about 7-8 weeks. They reach adulthood in two years and the average life span ranges from 5 to 7 years. Adult size is generally 1-to-2 inches (3-to-5 cm) in length.

Tree frogs hibernate on land, usually buried under leaf litter, fallen logs and other materials. Their bodies produce glycerol, which is converted to glucose. Large amounts of glucose in the frog’s vital organs acts as an antifreeze. Ice crystals will form in the body cavity and under the skin, but the lungs and heart are protected from freezing, and stop functioning until spring. Warm weather will thaw the frog and it will revive and continue its life. Gray tree frogs live in eastern North America from New Brunswick to Manitoba, south to northern Florida and west to central Texas.

*Young gray tree frogs are often bright green.*

Summer Afternoon Country Walk

The scent of sweet clover, insect songs and heat ride the wind along this country road.

The farm road near our cabin is bright, hot and breezy on high-summer afternoons. Musical chirps, metallic clicks and shrill whines of crickets, grasshoppers and cicadas wash over the fields. At mid-August, bird song is minimal — a few call, but do not sing. Most vocal are American goldfinches, with their lilting calls and flight. There are eastern bluebirds and an eastern kingbird. A broad-winged hawk circles a few times whistling its high, quavering note.

The dairy farmer who owns these fields, borders them with several feet of perennials — common milkweed, red clover, rabbit-foot clover, monarda, native sunflowers, blue vervain and goldenrod. Not only do these swaths of plants help stop runoff and pollution into the nearby Snake River, they also support bees, butterflies and other pollinators. Today, painted ladies, monarchs, eastern-tailed blues, yellow sulfurs, cabbage whites and mourning cloaks zip quickly through the hot, sunny air. Painted ladies dominate the aerial dance. Dozens swoop and swirl around us in the roadside flowers, and fly up from the wet, sandy road where they drink water and minerals.

Painted ladies (Vanessa cardui) nectar on prairie fleabane (Erigeron strigosus) in the field borders, which are critical habitat for many forms of wildlife.

Common milkweed (Asclepius syriaca), a crucial source of nectar for monarchs and other pollinators, borders fields of corn and soybeans.

The road winds into groves of hardwoods along the river. Red and white oak, basswood, willow and silver maple shade the road and lower the air temperature by several degrees. Now goldfinches are accompanied by the nasal “yank-yank” call of white-breasted nuthatches, scrappy blue jays and the gurgling calls of tiny black-capped chickadees. The woods are much cooler, still lush and green with ferns, river grapes, Canada ginger, false Solomon’s seal, and the ripening green-blue berries of sarsaparilla. Mushrooms pop up in shady, damp areas and I spot russulas, white puffballs, bracket fungi and others whose identity I don’t know.

Oaks, basswood, and maples arch over the road along the Snake River. Their shade refreshes us on this sultry afternoon.

Ferns and Canada ginger (Asarum canadense) flourish with oaks near the river.

Russala mushrooms are bright spheres against green moss.

The week’s thunderstorms raised the river more than a foot. Water burbles and tumbles over rocks and riffles. Ospreys, eagles and belted kingfishers frequently fish these waters. I hear the kingfisher’s rattle offset by the more plaintive calls of the larger birds of prey.

Water tumbles over river rocks and creates a bubbling melody.

A bald eagle (Haliaeetus leucocephalus), clutching its fishy catch, perches momentarily in a riverside silver maple.

We leave the woods and river once again and return to the hot August sun and breeze. I close my eyes and stand quietly. The wind ripples fields of hay, soybeans and field corn. It smells so good — ripe grain and grass, damp earth and sweet clover. I memorize the scents, sounds and heat of high summer. I will hold them close when the inevitable winter returns.

Native black-eyed Susan’s (Rudbekia hirta) spring up along most country roads in August.

White sweet clover (Melilotus Albus) scents the air along the road.

Wind, sun and insect song create a peaceful setting along a rural road in Central Minnesota.

August 4, 2020 by Beth

Butterfly Sampler

A painted lady (Vanessa cardui) basks in the sun on a roadside rock to warm its flight muscles.

Like miniature floating tapestries — stippled, spotted and striped — they decorate gardens, yards and roadsides. Butterflies are plentiful this summer. Alongside the bumblebees, they pollinate many flower species and aid with seed production. But honestly, I love them more for their color, grace and elusiveness; for the joy they evoke in the eyes of children and the hearts of people of all ages. I delight in the first and last of every season — often a mourning cloak or red admiral in late April and a tortoise shell or red admiral in October.

Here are a few of the butterflies I’ve seen recently:

Eastern-tailed blues (Everes comyntas) are active May – September in the Upper Midwest and southern Canada.

This hackberry emperor (Asterocampa celtis) was attracted by sweet apple juice in my pail of apple windfalls.

Mourning cloaks (Nymphalis antiopa) overwinter as adults and are often the first butterfly active in April. They favor oak and maple sap; watch for them at woodpecker drill holes.

Two rows of yellow spots on the forewing distinguish the black swallowtail (Papilio polyxenes) from the eastern tiger swallowtail female dark form (Papilio glaucus).

This female monarch (Danaus plexippus) deposits an egg on the underside of a common milkweed leaf.

White admirals (Limenitis arthemis arthemis) are common in areas with aspen and birch. They prefer sap over flower nectar.

Red-spotted purples (Limenitis arthemis astyanax) are a southern subspecies of white admirals and the two often hybridize in the Upper Midwest. This one’s wings show that it has survived a bird attack.

Banded hairstreaks (Satyrium calanus) lay their eggs on oak trees. This adult rests on common milkweed in our garden.

Eastern tiger swallowtails (Papilio glaucus) favor nectar from Joe-Pye weed, blazing star and phlox.

Red admirals (Vanessa atalanta) migrate north in April and usually depart in October. Their caterpillars feed on nettles.

July 9, 2020 by Beth

Ebony Jewelwing

What do you associate with the words “winged beauties”? Many would answer birds and butterflies — and I’d add damselflies and dragonflies, too. On a sunny, warm morning, a pair of inky black wings flutter near the Snake River. At first I think it’s a butterfly, but a closer look reveals the electric-blue-green body of a male ebony jewelwing damselfly; he flashes cool and iridescent in the morning sun.

Inky black wings and a blue-green abdomen identify this male ebony jewelwing (Calopteryx maculata).

A member of the broad-winged damselflies, ebony jewelwings fly more like a butterfly than like their dragonfly relatives. Their wings are 1-to-1½ inches long and their body length is up to 2¼ inches. The male’s colorful abdomen — green, teal, blue, even a hint of purple — shimmers in the sunlight. A female ebony jewelwing is similar in appearance, but not as showy as a male. Her body is brown with little bits of blue or green. Her wings are more transparent black and display a distinct white spot near each tip. (See a female at Wisconsin Odonata Survey.)

In the eastern United States and southeastern Canada, look for ebony jewelwings perched along shady banks of shallow streams and slow-moving rivers from late May until September. Adults live for about 20 days. A mating pair will often fly attached in the heart-shaped “wheel formation” and remain connected for several hours. Females deposit eggs inside of submerged water plant stems in quiet sections of streams or rivers. The larvae or naiads live in the water for about a year and eat other aquatic larvae, such as mosquitos and mayflies. Adults eat most soft-bodied insects, for example small moths, mosquitos, mayflies, gnats, flying ants and termites.

The Snake River in east-central Minnesota provides the habitat needed by ebony jewelwings.

Even though jewelwings are voracious predators, they serve as supper to other creatures — turtles, frogs, fish, bats and birds, such as red-winged blackbirds, blue jays, flycatchers, purple martins and kingfishers.

How does one distinguish between a damselfly and a dragonfly? A few simple differences make it easy to tell them apart. Generally, damsels hold their wings folded vertically above their body, while dragons spread them horizontally when resting. Damselfly abdomens are more slender than the stout dragonflies’. Damselfly eyes are set far apart on the sides of the head, but dragonfly eyes wrap around and touch on top of the head.

A green darner dragonfly (Anax junius) exhibits the horizontal wings, stout body and wrap-around eyes characteristic of dragonflies.

Vertically folded wings, a slender body and eyes set far apart on each side of the head are characteristic of the ebony jewelwing and other damselflies.

Damselflies and dragonflies belong to the order Odonata, which means “toothed ones.” Many come in beautiful, iridescent color combinations. Fossil records indicate that Protodonata, the ancient ancestors of both dragons and damsels, arose about 325 million years ago. The first Odonata fossils are dated at a little older than 250 million years, which means they’ve inhabited Earth’s skies since before dinosaurs existed. I love to watch and think about these ancient, graceful creatures that add so much beauty to our woods and gardens.