a pretty pest

Fall blooming plants attract such an interesting variety of pollinators.  Among the many species I was able to capture with my macro lens last week was this very pretty moth.

Flowerflies, or hoverflies as they are often called, feed on plant nectar and pollen. Their larvae, however, are often carnivorous and devour many species of plant pests, like aphids.

I didn’t know what this species was, and was surprised to see a moth out in the daytime.

There are a few moth species that do forage in the daytime, but this one really is largely a nocturnal forager and disperser, quite distinctive with its well insulated body of fuzzy tan “hairs” and huge green eyes.  It’s a corn earworm moth — the larvae of which are major agricultural pests on a variety of crops, especially corn, tomatoes, and cotton.

Corn earworm moth, Helicoverpa zea

Adults feed on flower nectar, but the larvae are not at all fussy about the host plant they feed upon. You have to admit, it’s an attractive looking moth, although its prodigious reproduction and polyphagous (eat lots of different plants) larvae make it a real threat to agricultural production.

As a major pest of commercial crops, corn earworm has been subjected to pesticide exposure for years, and over generations, the larvae have developed resistance to some pesticides, which makes controlling them even more difficult.  Each female can lay 500-3000 eggs in her lifetime, and the combined damage of corn earworm larvae runs in the 100s of millions of dollars in the U.S each year.

Fortunately for us (in the northern midwest), corn earworm is not a permanent resident but must re-invade with short, northerly directed migratory flights each summer.  They cannot survive sub-freezing temperatures and will die off each winter.

it’s not a bee…

Among the many insects buzzing around the fall blooming plants, especially the asters, daisies, and stonecrop (Sedum) are the flower flies (Heliophilous species).  I caught some of their feeding action with my macro lens the other day.

Hoverfly -Heliophilous fasciatus?

Flower flies, or hoverflies as they are often called, feed on plant nectar and pollen. Their larvae, however, are often carnivorous and devour many species of plant pests, like aphids, during their development.

Slightly smaller than a honeybee, this particular species of hoverfly looks very much like a bee with its yellow and black striped abdomen.  But they lack stiff hair-like insulation of bees, have much larger eyes, and only a single pair of wings that project outward from the body when the fly is at rest, instead of folding over the abdomen as those of bees do.  Nevertheless, the bee-like warning coloration and their hovering habit may protect them from naive insect predators.

Hoverfly -Heliophilous fasciatus?

Hoverflies make an up-and-down motion with their body to insert their proboscis deep into the disc flowers of asters.  They turn in a circle systematically probing all of the flowers before moving on.

Hoverfly -Heliophilous fasciatus?

The proboscis and tongue extension are relatively short and quite wide. Halteres (ovoid, silvery structures located just behind the wing) are modified hind wings that control the fly’s balance in three-dimensional space.  They vibrate along with the forewing; sensory organs at their base detect the fly’s position in space to correct or modify the action of the forewings.

Hoverfly -Heliophilous fasciatus?

Although the proboscis looks like a continuous tube, it seems to have some rough edges to it.

Unlike hummingbirds, hoverflies don’t hover to feed, but the males often do hover over their territory, moving quickly up, down, backward, and forward to fend off intruders, or perhaps to show off for females.

Mr. Not-so-beautiful

This is the time of year we see beautiful and dramatic color changes in the vegetation, but that is just one of many fall transformations.  Gaudy male ducks that shed those brilliant colors right after donating their sperm to the next generation last spring and became pale, cryptic versions of their previous selves have recently begun the transformation back to splendid technicolor.  It’s like a before and after makeover for Mallard Ducks at the local reservoir this week.

molting mallard ducks

In the summer, male Mallards look just like their females, with mottled brown plumage that blends in nicely with the dappled shade in which they spend the day.  The male of this pair (in the back) is just beginning to acquire the lustrous green feathers that will eventually cover his entire head.

Most ducks undergo two feather molts during the course of one year:  one in the spring/summer after breeding in which they replace all of their feathers, including flight feathers (resulting in the basic/female-type plumage); and one in the fall/winter in which they replace just the body feathers to regain the colors of the breeding (nuptial) plumage.

mallard plumage sequence-illustration by Patterson Clark

Mallard plumage sequence-illustration by Patterson Clark (Washington Post, Aug. 30, 2011).

This process of feather replacement ensures that birds acquire a new set of flight feathers before making short or long-distance migrations in fall or spring. More importantly, it ensures that gaudy male ducks, who would be conspicuous targets for aerial predators (like Bald Eagles) can protect themselves with better camouflage while they are flightless and molting a completely new set of wing feathers.

molting mallard ducks-

He’s sort of an ugly duckling at this stage of feather replacement, hence Mr. Not-so-beautiful…

Fueling this feather replacement not only demands additional energy intake per day, but a higher quality of protein in the diet, and so ducks will start feeding on more invertebrates and less pond scum, as they drop old feathers and grow in new ones.  It has been estimated that ducks need to ingest about 100 grams of protein to replace the 60+ grams of body feathers during a whole body feather molt.  That means they need to ingest more than 3 grams of protein per day over the 30 day molting period, and that translates to about 31,000 invertebrates eaten over the month!!!, according to the folks at Ducks Unlimited.

mallard-drakes-

Soon, the local ponds and lakes will have congregations of brightly colored males swimming around the few females (lower right corner) in attendance.

mallard-males-displaying-

And as spring rolls around again next year, the brightly colored male Mallards will begin to play “who’s the prettiest” again.

losing their spots

Signs of fall are beginning to appear as a few maple trees show some red and gold color in their leaves, the squirrels are busy collecting nuts off the trees, Canada Geese fly in V-formation overhead, and a few of the wildlife start growing their winter coats.  I first noticed the latter when the fawns suddenly appeared in the backyard without their spots.

White=tailed fawns-fall molt-

Just a trace of spots linger on the flanks of one of the twin fawns that have ravaged my wildflower garden all summer long.

White-tailed fawn - winter molt

The tawny brown coat with white spots is slowly being overgrown by the longer gray brown winter fur, which provides the deer with much needed insulation to survive the cold.

White-tailed fawns - winter molt

Not all of the fawns have started growing their winter coat, though.  It’s interesting that in these twins, one is clearly well ahead of the other in development of the winter fur — which lends further proof to the observation that twin fawns are usually fraternal, not identical.

What this tells me is that there have been at least two sets of twin fawns that have been eating up the backyard garden — and I thought it was just one hungry pair that had been doing all the damage.

butterfly “bushes”

Late summer flowers are attracting an abundance of bees and butterflies to residential gardens now, but by far the most attractive flowers seem to be those of the succulent Stonecrop (Sedum species) and Violet butterfly bush (Buddleya species).  Late summer generations of American Painted Lady are passing through the area in great numbers, probably on their way south to warmer winter climates.

american painted lady-

A Painted Lady delicately inserts its proboscis into each open flower on a gigantic blooming head of Stonecrop.  They are easily recognized by the owl eyes on the underside of their hindwings and orange and white splotches of color on the topside of their forewings.  Newly emerged butterflies are brightly colored with entire margins of their wings intact. 

american painted lady-

Apparently they like the nectar of Zinnia flowers as well.

But it’s the butterfly bush (Buddleya species) that is the most popular with the butterflies.  The large Eastern Tiger Swallowtails have a size advantage and might try to monopolize a flower spike,

eastern tiger swallowtail-

This female Eastern Tiger Swallowtail looks a little beaten up with frayed hind wings. The eggs she will lay or has already laid will develop through the caterpillar stage and into pupae that overwinter as a chrysalis. These butterflies don’t migrate.

but the fast-darting American Painted Ladies just skip around and beneath them to feed.  You can tell this is a butterfly flower from the flatenned floral disk with a thin, elongate flower tube that likely has a nectar reward at its base.

eastern tiger swallowtail-feeding on butterfly bush (Buddleya species)

The swallowtail has inserted its proboscis deep into one of the flowers (I colored light blue) of the flower spike.  Long, thin floral tubes like this would exclude almost all of the bees and flies and are probably much too narrow for hummingbirds to utilize.  Thus — an exclusive butterfly resource.

silver spotted skipper-

A Silver-spotted Skipper tried to feed on the butterfly bush along with the other butterfly species, but seemed to be excluded or chased off. So, it settled for whatever the Hosta flowers had to offer.

a beautiful riverside wildflower garden

What a surprise to find a lush wildflower garden growing in the damp soil at the edge of the St. Croix river at the Arcola Bluffs trail.  A trail along the river’s edge led me through dense clumps of Cardinal flower, Blue Lobelia, Obedient plant, and Prairie Ironweed.

cardinal flower-Lobelia cardinalis-

There were hundreds of individual Cardinal flower stems growing here in the semi shade and moist forest soil along the St. Croix river.

cardinal flower-Lobelia cardinalis-

With this many attractive red flowers, you would expect to see hummingbirds, and sure enough they showed up right as I began noticing the dense flower patch.

ruby-throated-hummingbird-on-cardinal-flower-1

Shot earlier in my backyard wildflower garden, but Ruby-throated Hummingbirds do love this plant.

white cardinal flower-Lobelia cardinalis

Among the hundreds of individual plants, there was one genetic mutant, a white form of the Cardinal flower.

White mutants of brightly colored animals or plants are usually genetic recessives, and are rare in the population. I imagine hummingbirds might skip over the nectar resources in this plant (wrong color to attract them), so it might not set much seed, which further contributes to its rarity.

Blue Lobelia - Lobelia siphilitica-

Another Lobelia species, the Blue Lobelia, was also growing in the riverside wildflower garden, although in much lower density.

Obedient plant - Physostegia virginiana-

I spotted just a few individuals of Obedient plant in this “garden”, although this plant is usually an aggresive colonist of open spaces in my backyard wildflower garden.

Prairie Ironweed - Veronia fasiculata-

Prairie Ironweed seems to like the wet river bottomland as well as it does the open prarie habitat. It’s large flowerheads were particularly attractive to honeybees.

Prairie Ironweed - Veronia fasiculata-

Has this lovely wildflower garden always been here? Did I just happen to hit it during its peak flowering? Other wildflower enthusiasts have reported lush blooms of cardinal flower along the backwaters of the Mississippi and St. Croix recently (late July-early August), so maybe I have just never discovered these little patches of colorful diversity along the rivers.

good morning, little blue bird

Indigo Bunting

His tail looks a little worse for wear, but he has maintained the deep blue color of his body feathers throughout the summer.

I was barely out of my car at the Old Cedar Road parking lot when a beautiful Indigo Bunting hopped up on a tree nearby, posing briefly in the bright sunlight before flitting off into the forest.  What a nice treat for the first bird of the morning.

Indigo Bunting

In fact, he is a surprisingly uniform blue.

In the next few weeks, this colorful male will molt into its winter plumage and become drab brown, like the female, before migrating to its winter home in Central America. Indigo Buntings, like most other bird species, replace their feathers twice a year, but these brightly colored males take at least two years to become completely blue.

the not-so-secretive Sora

Soras are a type of marsh bird that I rarely see because they are usually tucked away deep in the vegetation, obscured by tall stems and leafy plumes.  But this morning, a couple of Soras ventured out into the open water on the edges of the Mississippi marshes to forage, seemingly oblivious of the much larger ducks and geese around them.

Sora

Soras are a type of rail related to coots, moorhens, and gallinules.  They have a distinctive triangular shape, yellow bill, black mask, red eyes, yellow green legs with long toes, and usually carry their short tail feathers straight up in the air.

Sora

Mottled, rich brown feathers on their back help them blend into the edge of the marsh where they forage and nest.

Soras typically grab insects or seeds from the top of the water, occasionally probe into soft mud, walking quickly through the water and vegetation.  The adventurous Soras I watched this morning walked right up to and around resting ducks, paying no attention to their greater bulk, as they searched for hidden food items.

Sora and molting Wood Duck

The molting male Wood Duck seemed wary of the Sora though.

Sora and molting Wood Duck

Sora

Sora, just passing through…ducks don’t care

Sora

Long toes, with webbing between them, help Soras cruise through muddy muck of the marsh.

During the breeding season, we often hear the high-pitched descending notes of the Sora’s whinny call, but rarely seen them.  They are busy producing a lot of little Soras in a nest that might hold as many as 18 eggs, stacked in rows on top of each other.  Since the Soras start incubating before all the eggs have been laid, they hatch asynchronously, and the first youngsters to hatch jump out of the nest join one of the parents while the other parent continues to incubate.

Rumble.com produced an excellent video of Sora and Virginia Rails in their native habitat:

green on green

Hiding in plain sight by matching the color of your skin to the color of the background is useful for predators stalking their prey or prey trying to escape predation.  It’s also useful in confusing photographers about where to aim their cameras.  Case in point: I saw the bushes moving, wondered if it was a bird, thought it might be a chipmunk, but stared right at the little critter for a full minute before I figured out what it was.

gray tree frog-

A gray tree frog in green phase hiding in plain sight.  It wasn’t this obvious without the zoom on the camera to help pinpoint its location.

gray tree frog-

It’s scientific name gives a hint to its ability to change colors: Hyla versicolor. Usually it appears mostly gray with green splotches.

Many species of fish, amphibians, and reptiles have the ability to change color and outward appearance by contracting or expanding the chromatophore (pigment-containing) cells in their skin.  This chameleon-like ability can assist them in better regulating their body temperature, or as suggested, in achieving the kind of camouflage that helps them evade their predators or fool their prey. It is thought that the animals’ eyes perceive the color spectrum of their environment and send neural signals to skin chromatophores to effect the appropriate color changes.

In cases where there doesn’t seem to be a clear message about the color of the background, Gray Treefrogs are often mottled gray and green, or just remain gray, as illustrated below.

gray-tree-frog-

Hmm… water in a bird bath? Not sure what color to be.

gray-tree-frog-

Gray treefrog sitting on the side of a dish pan, next to green vegetation — again, it’s confusing about what color to be.

gray-tree-frog-

Gray treefrog sitting on an orange dahlia — no possibility of a match here.

gray-tree-frog-green-phase

Green-colored Gray treefrog on the ledge of a wooden door? Clearly a bad match.

the distraction lure

Some bird mothers go to great lengths to distract predators away from their nest and/or fledgling chicks.  They feign injury, flapping like they are wounded but can’t fly, chirping loudly to attract attention to themselves and away from their chicks.  I’ve seen Kildeer do this many times, as they lead me on a merry chase away from their nest.  For example…

But I’ve never heard of small songbirds using this strategy, until I saw it in action today when a female Indigo Bunting led me all over the backyard as I tried to find her nest and her chirping chicks.

indigo bunting-female feigning injury

Here I am, look at me, I’m helpless with my broken wings.”

Wings fluttering, hopping sort of helplessly through the grass, chirping continuously, and flying weakly from spot to spot, this female Indigo Bunting put on quite a show.

Moving around in the underbrush of the wildflower garden, I discovered two of her chicks, also chirping loudly, but hidden from view until one of them tried to cross a patch of grass.

indigo bunting-fledgling

Bunting chicks may fledge (leave the nest) after only 8 days, and can hardly fly more than 10 feet, so they tend to stay hidden in low, dense vegetation.

indigo bunting fledgling-

Not a very adept flyer yet…

indigo bunting-fledgling

The chick is not even fully feathered yet, has short stubby wing feathers, and no tail. It would be easy prey for a wandering cat…

Meanwhile, its mother is still chirping away at me, from all over the garden.

indigo bunting-female

first here…

indigo bunting-female

then here… (see that faint tinge of blue on her shoulder?)

indigo bunting-female

and finally right out in front of me.  Older females may be much bluer than this, with streaky blue patches on their shoulders, back, and tail.  But their overall drab plumage helps camouflage them while they care for the chicks.

indigo-bunting-male

A brightly colored male Indigo Bunting would attract way too much attention if he were feeding chicks in the nest.

Fun facts:

  • although Indigo Buntings are about the size of a Goldfinch and the female sort of resembles a female Goldfinch (but lacks those distinctive wingbars), they are actually members of the Cardinal family.
  • the blue color (especially evident in males) does not come from a blue pigment, but is due to special reflective particles in the feathers that scatter light and reflect blue wavelengths.  Read more about blue coloration in animals by clicking here.