Dragonfly

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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

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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

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Garden Bugs: Nifty or Nasty?

Like most of life, my garden is a mix of good and not so great: desirable plants and weeds, loamy soil and heavy clay, beneficial insects and annoying pests — and early August brought many types of insects to our garden. Here are just a few stand-outs.

Japanese beetles (Popillia japonica), an invasive species, are a type of scarab beetle that destroy many plant species in North America.

The biggest pest in our yard is the Japanese beetle, which skeletonizes the flowers and leaves of many plants. A few weeks ago they favored apple and crabapple trees, but I’ve also pulled them off of my rose, asters, day lilies and purple coneflowers. Now, they are shredding my hosta and anise hyssop blossoms. According to the Minnesota Department of Natural Resources, the beetles are native to northern Japan and probably arrived in a shipment of iris bulbs in 1916. They have no natural predators, although some birds, such as starlings, robins, bluejays and sparrows will sometimes eat the adult beetles and the grubs, which live in lawns.

Yesterday I picked 46 beetles off of my royal standard hostas. I used to squish them, but that releases their pheromones, which attract more beetles. Now I pick them off by hand and drop them in a small pail of soapy water, which kills them quickly without releasing their pheromones. I don’t use an insecticide because so many beneficial insects would die from the chemicals.

The convergent lady beetle (Hippodamia convergens) is a North American native that feeds on aphids, whiteflies and other pests.

Not all ladybugs are red or orange. The tiny esteemed ladybug (Hyperaspis proba) is black with yellow spots.

Unlike the Japanese beetle, ladybugs, or ladybird beetles, especially those native to North America, are beneficial to gardens. More than 500 species of ladybugs have been identified in the United States. Mom taught us never to harm ladybugs because they eat aphids, a major garden pest. Our native ladybugs don’t bite, so if you feel a pinch and find it’s from a ladybug, it is likely to be an Asian ladybug, which do nip — mainly because they seek moisture and salt, or they feel threatened. Asian ladybugs were imported in the 1970s to help destroy predators in agricultural operations. I let them be when I find them because they destroy so many aphids and other pests. However, the native ladybugs are better suited to our gardens and plant species.

Aphids, that favorite food of ladybugs, are tiny, often wingless, and very plentiful. There are more than 300 species of aphids in Minnesota and they are found on all types of plants. Most aphids on a plant are females that reproduce asexually, without having to mate. They also give birth instead of laying eggs. The newborns are clones of their mother, so they, too, are female. (Environmental conditions sometimes cause females to produce both female and male offspring, which are genetically identical to the mother, except that males lack one sex chromosome.) They come in many different colors. I’ve seen green, black, red, and I have orange ones on some of my milkweed plants. When aphids suck a plant’s sap, it causes curling, yellowing and browning of the leaves. Aphids also secrete a sticky, sweet liquid called honeydew. Last summer, during a heavy infestation of aphids, my milkweed plants were dripping with honeydew and covered with ants, which are attracted to the sweet liquid. Even though I washed the milkweed with water from the garden hose daily, the plants were disfigured and messy.

Tiny soft-bodied aphids (Aphids nerii) suck plant juices from common milkweed. The white specks are moltings that are stuck in the honeydew.

 

This juvenile male eastern pondhawk (Erythemis simplicicollis) will attack any type of insect its own size or smaller, including others of the same species.

In contrast to the slow, rather clumsy flight of beetles, several species of dragonfly dart and swoop among the garden plants. Perched on a milkweed leaf, a green eastern pondhawk zips lightning-quick from its perch to capture a fly. Its powerful jaws quickly crush and consume its prey. Common in gardens, dragonflies eat mosquitoes, gnats, flies and other insects. Their shining colors add beauty to the garden.

Most meadowhawks (Sympetrum spp.) fly in late summer and autumn.

Monarchs, red admirals and other butterflies are frequent visitors to our garden — especially now when the milkweed is blooming and the plants are in their prime for feeding monarch larvae. These tiny caterpillars feed only on milkweed and I discovered two of them a week ago. Adult monarchs sail through the garden stopping to nectar on milkweed, Joe-Pye, garden phlox and purple coneflowers.

Monarch caterpillars hatch and grow only on milkweed plants.

Adult monarchs (Danaus plexippus) and many other butterfly species nectar on common milkweed (Asclepias syriaca).

A red admiral (Vanessa atalanta) nectars on garden phlox (Phlox paniculata).

Red admirals are smaller and fly faster and more erratically than monarchs. A male finds a sunny spot and watches for a female to fly by. After mating, the female lays eggs on nettle plants. Adults nectar on milkweed, red clover, ripe fruit and tree sap. They are one of the few species that overwinter in Minnesota, often in a wood pile or mound of leaves.

The summer garden harbors so many interesting, and often beautiful, insects. Next time you’re working in your garden, or simply enjoying your yard, take a look at the diversity of these tiny creatures all around us. The majority of them are either beneficial or harmless. Nifty or nasty? You decide!

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Walk in the Woods

Oak woods are a cool place to hike on a hot day.

If you’re looking for a cool, peaceful place on a hot day, go to the woods. One recent morning, my husband and I walked in the woods of a Twin Cities nature center. Mature white oaks shielded the trail from the day’s growing heat. The woods were filled with birdsong and I “birded by ear” because the thick foliage hid their colorful bodies. I heard the songs of Baltimore orioles, rose-breasted grosbeaks, common yellowthroats, black-capped chickadees, house wrens, red-eyed vireos and many more. The only other sounds were the swishing of leaves and long grass in the steady breeze, and a few quiet “good mornings” from other walkers.

I love the lush canopy of green leaves untouched by any change of color. These trees are primarily white oak with an understory of dogwood, chokecherry, sumac and common elderberry. Though we hadn’t reached the peak bloom time of native wildflowers, a few species blossomed on the woodland edges: vervain, common yarrow, tick trefoil, water lilies, monarda and the year’s first black-eyed Susan’s. In the marshy areas, dragonflies hovered and darted like flashing jewels. We set our stride for a long, peaceful hike content to be still and absorb the quiet beauty.

Pointed-leaved trefoil (Desmodium glutinous) commonly grows along shaded woodland edges.

The tiny blooms of blue vervain (Verbena hastata) attract many native bees and small butterflies.

Black-eyed Susan’s (Rubeckia hirta) are a drought-tolerant and long-blooming species of coneflower.

Common yarrow (Achillea millefolium) was used to treat pain and inflammation in many cultures.

The red fruit of smooth sumac (Rhus glabra) feeds many birds and small mammals during the winter.

Widow skimmers (Libellula luctuosa) are large, slow dragonflies that can approach two inches in length. The white and black wing patches indicate this is a male.

Immature and female widow skimmers are brown and lack the white wing markings.

This dragonfly’s completely separated eyes indicate that it belongs to the clubtail family, possibly a lily pad club (Arigomphus furcifer) with its azure eyes.

An American water lily (Nymphaea odoranta) blooms in the shadows on a quiet lake.

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Garden Damsels and Dragons

A thread-slender eastern forktail (Ishnura verticalis) damsel fly.

A thread-slender eastern forktail (Ischnura verticalis) damsel fly.

The early morning garden is a place of shadows and peace. Cardinals, goldfinches, mourning doves and house wrens ring out their song in neighborhood trees. Already, bumblebees work the flowers — bluebells, bee balm, hyssop and milkweed — buzzing softly.  Almost camouflaged in the deep green shadows, a tiny damselfly perches atop a milkweed leaf. An eastern forktail (Ischnura verticalis), its slender body, less than an inch long, is mint green, blue and black. The wings are folded over its back in damselfly style.

Across the backyard, a much larger dragonfly relative hangs from the edge of a hosta leaf, wings held away from its body horizontally. It is a green darner (Anax junius), one of the largest dragonflies in the world at three inches in length and with a wingspan of more than four inches. Its spring-green head and thorax hide it among the hosta. It “wing-whirs”, or rapidly vibrates its wings to warm up its flight muscles — and that movement catches my eye and reveals its presence.

A common green darner (Anax junius) is one of the largest dragonflies.

A common green darner (Anax junius) is one of the largest surviving dragonflies.

Damselflies and dragonflies are members of the order Odonata, which means “toothed ones”. Unlike the peaceable bumblebees, they are fierce predators, hunting for small insects in the garden and eating many pests. Odonata are descended from some of Earth’s most ancient creatures. Fossils of ancient dragonfly ancestors (Protodonata) date back 325 million years. Scientists believe that bees evolved more recently — about 120 million years ago; the oldest bee fossil discovered so far is about 100 million years old. Both insect families contribute to a healthy garden.

 

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Rainy Evening Gift

The backyard was lush and green after the week’s heavy rain. The air felt chilly and damp as I picked up windfalls from our beacon apple tree.  Soaked, bedraggled bumble bees and long-horned bees clung to Joe-Pye blossoms and the undersides of leaves.  Only a few crickets chirped in the unusually cool August evening air.  As I reached into the garden to pull some weeds, I felt a fluttering against my fingers and heard the slightest rustle of wings.  Barely grasping my fingertips was a beautiful green dragonfly —a common green darner.  Its aqua-green thorax and dark maroon abdomen hinted that it was probably a female or juvenile.  I thought it was injured, or perhaps dying. Gently, I held my hand next to some sedum plants.  The dragonfly struggled onto the flower buds and I left it for the night.

Common Green Darner (Anax Junius).

Common Green Darner (Anax junius).

greendarner2a

In the morning, the green darner was gone.  I found no scattered wings or chitin, no other remains in the garden to indicate that it had been eaten. I believe that the sun’s warmth revived it.  Since then, I’ve glimpsed a large dragonfly zooming over the garden on several different days; perhaps it is the same one. I hope that it lives to make the long migration flight south to the Gulf Cost in September.

 

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Autumn Meadowhawk

The late afternoon September sun is warm and soothing.  Cicadas whine loudly and a monarch butterfly nectars in our patch of sweet Joe-Pye.  But another garden critter catches my eye this afternoon:  the yellow-legged meadowhawk dragonfly.

Adult male autumn meadowhawks are red with few or no markings on the abdomen.

Adult male autumn meadowhawks are red with few or no markings on the abdomen.

Also known as autumn meadowhawks (Sympetrum vicinum), their bodies flash gem-like red, orange and amber in the sun. Perched on daylily stalks, balloon flower seed pods and hosta stems, each dragonfly swivels its head watching for flies, small bees and wasps, and other soft-bodied insects.

Adult autumn meadowhawks are present from August into early November in Minnesota.  The species is common across much of the United States and southern Canada, and often is seen in yards and gardens. Their yellow or brownish legs set them apart from other types of meadowhawks, which have black or dark-striped legs. They also have minimal or no black marks on the abdomen.

Females are distinguished by the ovipositor visible near the end of the abdomen.

Females are distinguished by the ovipositor visible near the end of the abdomen.

When I see a meadowhawk flash in the garden, I think of the ancient history of these creatures. Scientists believe that early dragonflies (Protodonata) first inhabited Earth 300 million years ago.  They speculate that Earth’s warmer temperatures, and the atmosphere’s higher oxygen content, contributed to insects growing larger than today.  Fossils show that some ancient dragonflies had a wingspan of two feet. Today, most of the larger dragonflies have a wingspan of two to five inches, and meadowhawks are smaller yet at about one inch.  What they lack in size they make up for in the sparkle of sun on their transparent wings and the jeweled designs of their bodies.  And, after watching a meadowhawk grind up a small bee in its jaws, I’m glad they’ve evolved into smaller predators!

Sunlight captures the beauty of this meadowhawk's wings. The ovipositor and the light red abdomen with faint black markings identifies it as a female autumn meadowhawk.

Sunlight captures the beauty of this meadowhawk’s wings. The ovipositor, yellowish legs and the light red abdomen with faint black markings identify it as a female.

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Autumn Garden Creatures

Last Friday was a golden day with gentle sun, temps in the 70s and a southerly wind.  I walked at lunchtime and spent a few minutes in our back garden observing insects, birds and chipmunks.  It was the final day before a strong Canadian cold front and soaking rains moved in — and probably my last chance until spring to enjoy some of the garden’s inhabitants:

Autumn meadowhawk dragonflies, which fly late into autumn, still patrolled the garden.  The reddish-colored mature females, with clear wings tinted amber at the base and red spots at the top, added jewel-like color to the changing garden.

A male autumn meadowhawk dragonfly (Sympetrum vicinum) suns on a stone wall in the garden.

A female autumn meadowhawk dragonfly (Sympetrum vicinum) suns on a stone wall in the garden.

A celery looper moth visited the garden from morning until dusk each day for more than a week.  Though it’s not colorful, the contrast between the chocolate-brown wings and the bright silvery-white curved markings makes it glow in the sunlight.  Though looper larvae can be agricultural pests, the adults pollinate many varieties of plants.  This one seemed to prefer Sedum ‘autumn joy’.

A celery looper ( ) nectars on Sedum 'autumn joy'.

A celery looper (Anagrapha falcifera) nectars on Sedum ‘autumn joy’.

Celery looper

Side view of a celery looper moth.

Syrphid flies, also known as hover flies or flower flies, are small insects that zip between flowers much quicker than bees and wasps.  Syrphid flies are bee and wasp look-a-likes, but they don’t sting or bite!  Many species are helpful in the garden for two reasons:  The adults pollinate flowers and the larvae eat aphids and leaf hoppers, which cause a lot of damage and disease in plants.  They are called hover flies because they often hover in midair over the garden before zooming off in a new direction — sometimes flying backwards.  They are known as flower flies for their pollinating presence in the autumn garden.

A Syrphid fly, (Eristalis) pollinates native goldenrod.

A syrphid fly, (Eristalis) pollinates native goldenrod.

Another species of Syrphid fly pollinates garden asters.

Another species of syrphid fly (Helophilus) pollinates garden asters.

Hidden among the garden plants, an eastern chipmunk gathered seeds to store for winter use in its nearby den.  There’s a stable chipmunk population in our urban neighborhood, in spite of many gardeners’ attempts to eradicate the rodents.  At least the chipmunks retire to their dens until spring, unlike squirrels, which raid the garden during the growing season and the suet feeder during the winter months!

An eastern chipmunk surveys the backyard from its perch on our back steps.

An eastern chipmunk (Tamias striatus) surveys the yard from its perch on our back steps.

The backyard bird population is changing as many bird species migrate south.  For example, most of the warblers, orioles and swallows have left; ruby-crowned kinglets, yellow-rumped warblers and white-throated sparrows are passing through from further north.  Daily visitors to our garden, trees and hedges include northern cardinals, blue jays, American goldfinches, black-capped chickadees, white-breasted nuthatches, American robins and a brown creeper. I don’t have a telephoto lens yet, so I don’t photograph many birds.  An excellent website with photos, key facts, bird calls and other information is allaboutbirds.org.

Lastly, bumble bees and honey bees nectared on the Sedum ‘autumn joy’ and garlic chives. (Earlier in the summer, I pruned the sedum to different degrees so that it would continue to bloom late into autumn.)  The sedum and asters were the main attraction for insects last week.  I haven’t seen either bee species since the weather turned cold and rainy.  I miss their industrious presence and look forward to their return next spring.

A honey bee nectars on garlic chive blossoms (Allium tuberosum).

A honey bee nectars on garlic chive blossoms (Allium tuberosum).

A bumble bee (Bombus) nectars on Sedum 'autumn joy'.

A bumble bee (Bombus impatiens) nectars on Sedum ‘autumn joy’.

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Lake Darner Dragonfly

I love dragonflies for their aerial acrobatics, beautiful colors and ancient presence — they’ve flown Earth’s skies for about 300 million years.  In Minnesota, a few species of large, colorful dragonflies are active into October.  Last week I found a darner (Aeshna) dragonfly sunning itself on a nearby cabin.

A lake darner dragonfly (Aeshna eremita) rests in the sun.

A lake darner dragonfly (Aeshna eremita) rests in the sun.

Called darners for the resemblance of their long abdomen to a darning needle, the blue or mosaic darners can be confusing to tell apart.  I believe the one I photographed is a lake darner (Aeshna eremita), based on the notched side stripe, the vivid greenish-blue jewel-like coloration of the stripes, its length (about three inches) and its vertical perching position.  It flew away before I could get close enough to see its facial markings.  Lake darners are native to Canada and the northern United States, and are the largest species of North American darner.  They prey on mosquitoes, wasps, mayflies and most other kinds of soft-bodied insects.

Related Websites:

The Dragonfly Website includes a great overview of dragonfly facts in its “Frequently Asked Questions” section.

ARKive.org features a profile and photos of the lake darner, along with thousands of other plant and animal species.