Ode to the prairie

My husband loves prairies; he is an expert prairie biologist. So maybe this is an ode to him.

Last weekend we visited three prairies in northern and west-central Minnesota so Alison could capture the "essence of prairie" in digital form. See her Aug 30 post below for some dramatic examples. I thought I should add that we also saw some animals (besides cows) and some quite unexpected plants while walking around on some of the preserves. For example, do you know what this plant is? Not your typical prairie plant, but useful in many ways -- some illegal.

Sunset on the prairie makes it light up with color. As we were out driving the backroads at sunset we saw this male marsh hawk land in the grass. Alison and I hopped out of the car and tried to sneak up on him to get his picture, but alas he flew quickly away.

Dragonflies were especially abundant, and we managed to get close up to some different species than we see around the Twin Cities. This one was really huge (a whopping 3-4 inches) and extremely lethargic, and let me get right up in his "face".

like this.... I think this is a juvenile (just emerged) Common Green Darner, based on its gray- brown eyes with the yellowish rim, green thorax, brown abdomen, and bi-colored legs. The abdomen has a bright blue lateral stripe in adult males.

Another curious feature is the bulls-eye that appears in front of their eyes. I found a newly emerged Green Darner in my backyard the other day and got a better picture of the bulls-eye. I wonder what its purpose is.

Darners are one of the most common big dragonflies we see buzzing over the fields above our heads. Alison's prairie pictures (below) were full of dragonfly silhouettes. However, they never seem to tire cruising and darting and are hard to find at rest.

Here's another cooperative subject, a Band-winged Meadowhawk, sunbathing on the gravel near sunset. This is also a juvenile, based on its brown abdomen with black stripe. The adults have a red abdomen. The striking amber wing pattern is unmistakable for this species though. Like other meadowhawks, it hunts in low vegetation, bogs, and slow moving water. It is more common in the western US where it has less competition from other small dragonflies.

There were other meadowhawk species flitting through the low prairie vegetation as well. Alison found some individuals that are either Cherry-faced or Ruby Meadowhawks; apparently you can only tell these apart by looking at them under with 20X magnification.





The prairie is not just a flat pancake in northern and central Minnesota. Glaciers left numerous gravel (and boulder) deposits as they pushed south, while scooping out deep gouges that turned into pothole lakes. Drier hilltops and wetter creek bottoms add to the diversity of life that lives there. I had to watch where I was walking through part of the wetter prairie as we scared up frogs and toads. Sometimes they just hunker down and assume you won't step on them. This guy did not want to budge, even when I got my camera lens down 6 inches from his face.

The prairie is an interesting place to explore, and is certainly more diverse than you think when you drive by what looks like monotonous tall grass.

Here there be dragons

In this case, these are good dragons that eat many of those annoying mosquitoes over their several-month lifetime. Damselflies and dragonflies belong to a group of insects (Odonata) that are relatively ancient, and their preserved fossil forms from 300 million years ago look much the same as their descendents do today.

Two sets of wings (which can be operated independently of one another) gives them both speed and maneuverability, and like hummingbirds, dragonflies can fly forwards (at 100 body lengths per sec), backwards (3 body lengths per sec), and hover in place. They can dart out from a perch to catch small flying insects at speeds of 60 mph. Like birds, some dragonflies may hunt from a perch, turning their heads to follow potential prey then darting out to catch them, and returning to the perch to consume them. Other species primarily hunt from the air, cruising back and forth across the wetland to chase down those pesky mosquitos.

The most common species I've seen in suburban wetlands are these:

This is a male 12-spotted Skimmer (aptly named), which is easily recognizable from a distance because the white spots contrast sharply with the dark ones. Only males have the bright blue abdomen (females are duller in color). Skimmers perch horizontally while hunting, which enables amateur photographers to get good pictures of them, even though they are only 2 inches long.

This is a Widow Skimmer which hunts from the tips of weeds in open fields, rather than over the water like its 12-spotted cousin. Males defend small territories, but establish new ones each day, which I'm sure adds to their energetic cost of life.

This is a White-faced Meadowhawk, a small (1 inch) dragonfly common in the low vegetation where it perches to hunt. Being so small, they are vulnerable to predation by insectivorous birds, and therefore don't let you get close enough to get a good photo of them. For better pictures of meadowhawks, see photos of another St. Paul-ite at http://ecobirder.blogspot.com/2008/10/carpenter-dragonflies.html

And lastly, a small (1.5 inch) but very distinctive dragonfly that I only saw once out in a prarie field, the Halloween Pennant, so named because of the black and orange markings on the wings. As you can see in the photo, they hunt from the tips of flower or grass stalks.

Some interesting facts about dragonflies:
They spend most of their life in water growing to adult size; they molt (shed skin) 8-17 times, increasing in size with each molt. In northern climates, they may live 8 years as a nymph, but only one summer season as an adult.

The enlarged and clawed lower lip of dragonfly nymphs can shoot out in 1/100 of a second as far as 1/3 of their body length to snare small crustacean prey. In the absence of fish, they are the dominant predator in ponds.

The gills of aquatic dragonfly nymphs are located inside their rectum; they breathe by moving water rapidly in and out of the anus (note: fresh water turtles do this too).

One mating provides a female with enough sperm for her reproductive lifetime. Although mating events may last hours, the transfer of sperm to the female only takes a second. The rest of the time the male is most likely removing the sperm from any previous mating; his penis is highly modified with a brush that scoops up any sperm and ejects it.

Dragonflies have really beautiful, multifaceted eyes that are particularly
good at picking up motion.

To see some really nice HD photos, go here:

To see a slow-motion video of Dragonfly flight (from David Attenborough's "Life in the Undergrowth"), go here:

Japanese beetles -- Round 2

At first I thought they were pretty, now I hate them. When the Japanese beetles graduated from eating raspberry leaves to eating the fruit, I was willing to give some of it up because we had a bumper crop. But then they moved onto the roses. They especially love the white, pink, or yellow large-flowered hybrid tea roses, on which they seem to conduct mating orgies that involve devouring the entire rose.

I take my revenge by cutting the flower head and quickly submersing it (and the mass of beetles) in a container of soapy water to watch them drown. Soap seems to dissolve whatever cuticle lipids they have that allow them to float to safety. Soapy water kills them - yea! But, looking more closely I found that some sank immediately and others floated up at the boundary of the soapy foam. Why the disparity? What made some sink? Any ideas to explain the difference?

The birch trees are losing a lot of their top leaves to Japanese beetles as well. If you've noticed brown skeletal remains of leaves around your trees this summer, it's probably due to a JB infestation.

We need a very cold winter with no snow cover to kill off the larvae that will be developing in our lawns. I never thought I would wish for that!

Hooray For Hoverflies

I was sitting out in my garden with my daughter this morning, watching her enjoy the flowers, when suddenly, she ran away screaming. I asked her what had happened, and the best I could get out of my two year old was, "Scary Bee!" I happen to love trying to photograph bees, because I think they are lovely and such interesting insects. I love trying to capture their amazing eyes and all the pollen on their legs, so I grabbed my camera and my macro lens (although, I'm lacking a tripod at the moment - and that would have helped immensely). As I got closer to her "scary bee", I noted that it was not a bee that she had seen but one of the very friendly and helpful Hoverflies that inhabit my garden. I can see why she was confused - upon closer inspection they look quite a lot alike - although the Hoverfly is quite a lot smaller and hovers above the flowers whereas the bees simply buzz around.

(Click pictures to view them larger)







Then, as I was photographing this first one, another one landed on the flower next to him. At first, I thought it was actually a bee, because he was the same size as a bee, but I later learned that bees and wasps all have two sets of wings and flies only have one - so this is just a different species of hoverfly. Notice how much bigger he is compared to the brown part of the flower than the first guy? He's significantly bigger - and much easier to photograph. He also didn't hover the way the smaller fly did - and I have been told it's because hovering requires large amounts of energy and therefore cost prohibitive for such a large fly.







And one last one, because I love all the pollen stuck to his rear end:



What I love most about these syrphid flies (and probably what most farmers love most about them as well), is that although the adults eat mostly pollen and nectar, the syrphid maggots eat lots of other things that we consider pests - like aphids. Have a problem with aphids destroying your garden? Plant some plants that attract hoverflies nearby:  alyssum, Iberis umbellata, statice, buckwheat, chamomile, parsley, and yarrow.

Despite how much they may resemble honeybee or wasps, hoverflies don't have a stinger and pose no risk to humans at all. So, if you, like my daughter, flee at the sight of anything black and yellow, take a closer look and enjoy watching this busy little insect pollinate your garden.

If you want more information on the subject, it just so happens that my sister did her Ph.D. thesis on the the Syrphid Flies, so I'm sure she would be happy to post a link to her research.

Butterfly afternoon

Torrential rain has kept me indoors most of the time for the past two days, but the sun came out this afternoon, and I noticed that the milkweed was chock-a-block with insects swarming the blossoms. They were probably overfull of watery nectar after all that rain. Along with the usual complement of wasps, small bees, and monarch caterpillars, four species of butterflies were foraging intensively, and there were several individuals of each.

The Monarch butterflies were bossy and kept chasing the others away, but with four bushy clumps of milkweed plants, they couldn't exclude all the other foragers.



The Swallowtails were back, but only a single individual at a time.

Two new species appeared in the mix, and I had to look them up to be sure who they were. Here's a good website to do that. http://www.butterfliesandmoths.org/ . Go to the Image Gallery if you just want to compare pictures with what you see outdoors.

This is a Red-spotted Purple (I've never seen one of these before). Handsome, isn't it?

And this is a Red Admiral (they are pretty common), and I found them on the Coneflowers and the Blazing Star today also.

The Red Admiral was very cooperative and let me take a lot of pictures of its bizarre facial features. Check out those ropey antennae with the bullbs on the end and his funny-looking face in this profile. His eyes look like they have slits, instead of the usual compound facets. That yellow thing coming out of what looks like his turned up nose is the proboscis that it stuck down into the flower to slurp up the nectar. You can see a few of the milkweed's yellow pollen sacs stuck to his legs.

A beautiful afternoon for butterflies.

(P.S. If you click on the image, you'll get an enlarged view.)

The Beautiful but Poisonous Milkweed

Its flowers smell like perfume, its colorful blossoms and abundant nectar draw a variety of insects to it.

But only a very few species can tolerate eating the milkweed, because a cut leaf or stem produces a sticky, milky, alkaline sap that is full of toxic chemicals. Monarch butterflies and their larvae seem to tolerate these nasty substances (called cardiac glycosides), and actually sequester them in their body, so that if a naïve predator like a young blue jay tries to eat them, the bird’s digestive system immediately rejects the caterpillar and the bird spits it out. This might not save that particular caterpillar or butterfly, but the bird won’t try eating another one of that kind and remembers “orange and black – don’t eat that”.

This week the first caterpillars showed up, one I had expected, and one I had never seen before.

This Monarch caterpillar is probably just a few days old. In a week or two, it will look more like this one below.



And then I walked over to another clump of milkweed across the yard and found this clump of larvae that had eaten the milkweed leaves literally to the "bone". They had almost completely defoliated the plant.

A little closer view of these half-inch long fuzzy larvae. Turns out these are the Tufted Milkweed Moth (Euchaetes egle). The female lays her monster clutch of eggs on plants without Monarch larvae, which is a good thing since this enormous group are voracious eaters. I captured this bunch and put them in a rearing cage with a couple of 2-foot long milkweed stems, and they managed to demolish all of those leaves in less than two days.

The milkweeds are forming small pods of seeds now, and soon another group will arrive to monopolize these plants – the milkweed bugs.



Milkweed bugs are seed predators and, like the Monarchs, they arrive by migration from points south, in time to harvest the seed crop. It’s always amazing to me that these insects can hone in on scattered patches of milkweed as they move through an urban area like this one. The picture above was taken last August when the pods had matured. Adults and nymphs feed communally on the seeds; they stick their mouthparts through the pod wall, secrete salivary enzymes to digest the seeds, and then slurp back the digested nutrients. We've only seen milkweed bugs on plants in Minnesota the last few years; perhaps its the change in climate that makes it possible for them to come this far north.

Backyard Pollinators

The wildflower garden is almost at maximum flowering, and we’re seeing increasing numbers of butterflies, wasps, bees, flies, and beetles swarming the colorful bouquets.



We haven’t seen honeybees in the garden for several years, but pollination efforts have been amply taken care of by a variety of hymenoptera from tiny sweat bees to larger bumblebees and several types of wasps as well.

The swamp milkweed is in full flower, and emits a sweet fragrance that pulls in quite a few different pollinators, as well as a specialized group of munching herbivores that are
well adapted to handle the toxic cardiac poisons (glycosides) it sequesters in its leaves and stems (but perhaps not its flower nectar).   Yesterday, the plants were full of
bald-faced hornets, a long legged black and white wasp (not a hornet taxonomically speaking), known for its painful, repetitive stinging ability.  They are social and nest in a large papery hive constructed by all the workers, but they seemed to aggressively exclude each other from the particular flowers on which one is foraging.





My camera equipment is inadequate to get good closeups of this less than 1-inch long insect, but this photo shows the striking black and white coloration well);  from (http://bugguide.net/node/view/279221/bgimage).  For more information and some really great close-up photos, go here:  http://www.cirrusimage.com/Bald-faced_hornet.htm .

The hornets moved pretty quickly around each flower cluster, thrusting their heads deep into each flower as they moved along.  It was somewhat comical to watch them try to leave that flower cluster, because the milkweed flower has a unique pollination mechanism that traps the insect’s leg in a tiny cleft where they get stuck until they are able to remove the saddlebag of pollen in that cleft.  The hornets pulled, twisted, buzzed, and hung from the flower until they could manipulate it just right to escape.  Most of the hornets had multiple bags of pollen attached to the spines on their lower legs (which you can faintly see as light yellow oblong structures attached to the end of their leg).



The milkweed’s strategy is to reward the insect with just a drop of nectar so that
it moves to other flowers, gets its leg stuck once again and deposits the saddlebag of pollen in another, different flower and… voila, pollination.

Bumblebees avoided the milkweed preferring the bee balm and the coneflowers instead.  These flowers don’t seem to offer much of a nectar reward because the actual flowers in the composite head are tiny and narrow. However, it turns out that bumblebees have really long tongues, complete with little brushes on the end of them, that enable the bees to reach into a narrow slot and slurp up even the tiniest drop (http://www.bumblebee.org/bodyTongue.htm).  They are pretty hard to photograph close up, because they are continually on the move, testing each flower in the head for
nectar and stopping only infrequently in any one flower for just a few seconds.

Below - bumble bee on purple coneflower:





Above:  bumblebee on Bee Balm (Monarda)

It is due primarily to the services of our local bumblebees that we had such a fine raspberry crop this summer.  In June, the raspberry plants were thick with several species of bees, but the bumblebee, in particular, is an incredibly efficient pollinator.  Apparently they develop electrostatic charge as they fly, so that when they land on a flower, the pollen attaches itself to their fuzzy thorax and leg spines.  When they move on to another flower, the receptive stigma of that flower attracts the electrically charged pollen away from the bumblebee, and again, voila…pollination.  Another amazing feat bumblebees perform to collect pollen (which they feed to their larvae) is to “buzz” the flower at a frequency that causes the pollen sacs on the flower’s anthers to open and dust the bee. The bees groom themselves when they get back to the nest, depositing their pollen for workers to feed the larvae.  However, while out foraging, there is an abundance of pollen on them that finds its way onto theappropriate flower receptacle.  Some people claim that these characteristics make bumblebees far better pollinators than honeybees.

Alien Invaders

Have you seen these in your yard or on the golf course this
summer?



The Japanese Beetle is an attractive insect, but a destructive one. Look what they've done to the leaves of one of my raspberry plants.



The beetle has been in the US since the early 1900s, but occurs primarily east of the Mississippi River in growing numbers.  We seem to have a particularly heavy infestation in the Twin Cities this summer.  Larva overwinter as pupae in the lawn soil, emerge as adults in the spring, mate on various sorts of plants as they eat through its leaves, lay their eggs in your lawn, and the larva grow up feeding on grass roots until they enter a suspended state of metabolism during winter cold weather.   Plants the adults prefer to munch while finding a mate include roses and red raspberries, dahlias, hollyhocks, and hibiscus, and various trees such as Japanese maple (naturally), Norway maple, apple, and Crepe Myrtle, as well as soybeans.  They particularly like fragrant roses; one of my white roses had so many beetles chomping away inside the petals, it looked like it was animated by Harry Potter magic.



How do you get rid of them?  In Japan, they are controlled by their natural predators and parasites, but in the U.S., unless there are huge infestations with risk of crop damage, affected plants are usually not treated.  To read more about its control, go here:

It is also suggested that the best control is to use landscape plants that don’t attract the beetles, like red maple, boxwood, redbud, dogwood, burning bush (Euonymus), juniper, spruce, and pine or flowering perennials like ageraturm, columbine, begonia, lily of the valley, coreopsis, larkspur, foxglove, and hosta.