bugs on parade

I have seen a bonanza of interesting insects lately on early evening walks at the local marsh near my house, including some insects I had not seen before.

virginia ctenucha moth-

This is a Virginia Ctenucha moth — check out those antennae, which is how I knew it was a moth. A bright orange head and iridescent metallic blue body (seen when it flew) make this pretty easy to identify.

virginia ctenucha moth-

A closer look at the long, comb-like antennae and bright orange head of the Ctenucha moth.

Apparently these moths are quite common in the northeastern part of North America and range as far west as Manitoba in the north to Kansas in the south. They are day-flying moths that can be found in woodland and grassland nectaring on flowers, but their very hairy larvae grow up eating various grasses, sedges, and even iris in meadows.

bumblebe on crown vetch

Lots of bumblebees are out collecting nectar and pollen from the numerous wildflowers in bloom. This one seemed to find a nice supply of nectar in crown vetch, but obviously had been collecting a lot of pollen as well.

bumblebee and wildflowers-

These fields of wildflowers should be full of honeybees, but I rarely seen them any more, unless there are hives nearby.

red admiral butterfly-

A Red Admiral butterfly posed briefly on a leaf. This one seems a little tattered and faded, and more orange than red (or that could be the yellow light of the late afternoon sun).

pearl crescent butterfly-

Pearl Crescent butterflies nectar on a wide variety of flowers in grassy meadows. This one spent a lot of time investigating the flowers of Hairy Vetch plants.

The orange and black pattern of the wings is striking and makes them easy to identify, but what really stands out is those white beads on their very black antennae.

pearl crescent butterfly-

 A real beauty.

common buckeye-

Another rarely seen butterfly (at least by me) is the Common Buckeye. This one seems a little worse for the wear, with some bites out of its wings.  Eight distinctive eyespots on both the upper and lower sides of their wings make this species easy to distinguish.

pink clouded sulfur butterfly-

Pink Clouded Sulfur butterflies have a fine pink edging around their wings and attractive green eyes. Late afternoon sun created a nice shadow image…

pink clouded sulfur butterfly-head-

And some deep pinkish red antennae to complement those green eyes and yellow bodies.

hover fly on sunflower-

A lone hoverfly was out late foraging on the tall sunflowers in the grassy meadow.

Specialists

Isn’t it strange that a plant that contains so many nasty chemicals (e.g., cardiac glycosides), as well as rubbery latex so alkaline that it can permanently scar the cornea of one’s eye, has so many insects that specialize on it?

But here they are — the amazing milkweed fauna:  lepidopterans, bugs, and beetles, consuming every part of the milkweed plant from its roots to its seeds — all seen in the backyard this summer.

milkweed-monarch butterfly larva

The familiar Monarch butterfly caterpillar, munches away happily undeterred by the milky latex exuding from the leaves and stems of the plant.

milkweed tussock moth larvae

The less familiar Milkweed Tussock Moth larvae — there were so many caterpillars on this particular milkweed plant, they completely defoliated it.

milkweed tussock moth larva

The tussock moth larvae grows some very long tufts and is not quite so gregarious when it’s older.

milkweed bug adults and nymphs

Milkweed bugs (true bugs — Hemiptera) are usually found on milkweed plants that have formed seed pods. They lay a clutch of bright yellow eggs on one of the pods, and the nymphs develop through five molts into adults by feeding through the pod wall on the seed endosperm.

aphis-nerii-cornicle-and-braconid-wasp

Yellow aphids collect on milkweed stems and pods, but feed on the sugars passing through the plant’s phloem vessels, not the seeds. Small wasps (left center) parasitize the aphids by laying their eggs on the host.  Aphids are actually true bugs (Hemiptera), although these non-winged individuals don’t appear very bug-like.

milkweed beetle-Tetraopes sp

The Red Milkweed Beetle is a member of the long-horned beetle family. They lay their eggs near the ground, and the larvae burrow into the roots and develop and overwinter there to emerge as adults the following spring.  Like the monarch butterfly larvae, milkweed beetles incorporate the milkweed’s poisonous chemicals into their own bodies, becoming distasteful to their predators.

milkweed-leaf-beetles-mating

Milkweed leaf beetles are members of the very large leaf-beetle family. They eat the leafy greenery, but the larvae are also known for consuming each other — their cannibalistic tendencies reduce competition for food in their local area!

Isn’t it ironic that in producing poisons to ward off herbivores, the plant becomes more attractive to specialist herbivores also trying to avoid predation?

Infestation!

Each year about this time, the swamp milkweed acquires an infestation of yellow aphids.  I don’t know where they come from or how they find the plants (chemical cues?), but they regularly appear just as the pods are elongating and maturing seed.

Aphis nerii on swamp milkweed pods

Aphis nerii, the yellow milkweed aphid, is a specialist that only feeds on milkweed species. Winged adults settle on the plant and then produce hundreds of asexual (non-winged) clones of themselves.

Usually I find the aphids just on the terminal stems and pods, but one plant had a congestion of aphids from the ground level, up the stem, to the tip of the pods.

aphid infestation on milkweed stem

It’s hard to believe the aphids get much nutrition from the woody part of the milkweed stem.

Aphis nerii on swamp milkweed

Aphids feed on milkweed sap by inserting their slender proboscis into the vessels that carry the sugar manufactured by the plant. Swollen yellow abdomens stick upright from the plant surface while their heads are down near the surface. When threatened by a potential predator (or human), they wiggle their butts in unison.

For more information on this interesting phenomenon, see my earlier post on how predators control the aphid population.

 

The woodpecker and the weevil

It’s unusual to see Downy Woodpeckers foraging on herbaceous plants in the middle of a prairie landscape, even if the flower stalks do reach 5-6 feet tall.  But the mature seed pods of Common Mullein may harbor a feast of insect larvae that Downy Woodpeckers have learned to harvest.

downy woodpecker on Common mullein

This Downy female spent quite a long time exploring every bit of all the Common Mullein flower stalks on a small patch of prairie. She worked around the bottom half of the flower stalks, then flew to the next stalk to start another search.

Common Mullein is a fuzzy-leaved biennial weed, introduced from Europe.  During its first year of growth, it produces a large rosette of furry leaves, followed by one to several tall spikes of small yellow flowers the following year.

downy woodpecker on mullein

Only a few small, yellow flowers open each day (and they last just one day), but the woodpecker isn’t interested in insects on the flowers.

Mullein is famous for its seed production — putting out as many as 175,000 seeds per plant.  But the woodpecker isn’t interested in eating the Mullein seed either.  But that much seed in one place becomes highly attractive to insects, like Mullein Weevils, whose larvae specialize in devouring mullein seeds.

downy woodpecker on common mullein

Each of the knobby seed capsules that surround the flower stalk harbors as many as 500-600 seeds. A weevil larva develops inside one seed capsule where it consumes 100% of the developing seeds, and finally pupates there. 

The lower and middle thirds of the Mullein flower stalk seem to suffer the heaviest infestation of weevil larvae, with the top being relatively weevil free.  In all, weevils destroy/consume about 50% of the mullein seeds, which still leaves a lot of seed production from just one plant (~80,000!).  But without this semi-effective control of mullein seed production, that species would be a lot more invasive.

Then as seeds are maturing, along come Downy Woodpeckers who probe the seed capsules for larvae and pupae, thus keeping the weevil population in check. A nice system of biological control at a couple of different levels.

Islands of(f) islands

“Great fleas have little fleas upon their backs to bite ’em,
And little fleas have lesser fleas, and so ad infinitum.”
(Victorian mathematician Augustus DeMorgan)

And so it seems true of islands as well … larger islands have little islands about them, ad infinitum.

Coastal and landform topography of Puerto Rico and U.S. Virgin Islands.  From NCCOS http://ccma.nos.noaa.gov/ecosystems/coralreef/summit_sea/summit_sea2.aspx.  Culebra and Vieques are the small islands just to the east of Puerto Rico.

Coastal and landform topography of Puerto Rico and U.S. Virgin Islands. From NCCOS. Culebra and Vieques are idyllic small islands between Puerto Rico and the U.S. Virgin Islands (St. Thomas, St. John, and St. Croix).

We got a great view of the chain of islets that span the distance between Puerto Rico and its small island neighbors to the east as we flew at 1400 feet over the ocean expanse to our destination on Culebra.

Cape Air took us from Puerto Rico to Culebra and back.  I remembered to get my camera out of the luggage on the trip back!

An 8-seater Cape Air plane took us on a half-hour flight from Puerto Rico to Culebra for a mere $45. I remembered to get my camera out of the luggage on the trip back to PR!

A view of Culebra looking northeast toward St. Thomas, U.S. Virgin Islands

A view of Culebra looking east toward St. Thomas, U.S. Virgin Islands.  The coastal shores and keys surrounding Culebra are protected as part of the U.S. National Wildlife Refuge system, which results in some of the most diverse and healthy coral reefs in the Caribbean and prime habitat for nesting seabirds.

A tiny islet in the channel separating Puerto Rico and Culebra (seen in the distance).

A tiny islet in the channel separating Puerto Rico and Culebra (seen in the distance). When is a rocky outcrop in the ocean too small to be called an island?

The extreme northeastern tip of Puerto Rico, showing coral heads and sandy shoreline that surround the island.

The extreme northeastern tip of Puerto Rico, showing coral heads and sandy shoreline that surround the island.

Although birds are highly mobile and able to navigate the mileage between mainland and islands fairly easily, there is nevertheless an ever diminishing number of species on islands as the distance from the mainland increases and/or the size of the island decreases.

Birds could settle on Caribbean islands by migrating eastward from Central Mexico (1026 bird species) or southward from Florida (510 species).  To illustrate the “island effect” of distance and size:  Cuba has 368 bird species in its 43,000 square mile expanse, while nearby but much smaller Puerto Rico (3400 square miles) supports 349 bird species, and Culebra (12 square miles) has just 110 species, many of which are only passing through on migration to other sites (only 43 species actually nest on Culebra).

Over time island birds often develop unique characteristics that separate them from their mainland ancestors, becoming unique to that particular place (endemism), like the Puerto Rican Lizard Cuckoo and the diminuitive Puerto Rican Tody (from an earlier post).

Looks very much like the Cuban Lizard Cuckoo, I photographed

Looks very much like the Cuban Lizard Cuckoo, I photographed last April.

All-Americans

but not of the athletic variety…

It's called an American Widgeon to distinguish the North American variety from the Eurasian one.

This duck is called an American Widgeon (Anas americana) to distinguish the North American variety from its similar-looking Eurasian close relative (Anas penelope).   Female widgeons look much like female mallards, but with a rounder head and a much shorter bill.

Here’s a duck that really likes its green vegetables and will graze happily in the water on aquatic plants or on land.   Their short, stubby bill provides the leverage to forcefully pull up plants other ducks cannot get.

With its

With the iridescent green stripe on the side and back of its head and a bold white forehead (reflecting a lot of white back at the camera), it is easily recognized among a big group of ducks.

Widgeons (both Eurasian and American) breed in the far northern temperate zone and migrate to southerly latitudes with open water for the winter.  Wikipedia says widgeons are highly gregarious outside of the breeding season, but this guy was all by himself.

An American Tree Sparrow

An American Tree Sparrow (Spizella arborea), looks nothing like a Eurasian Tree Sparrow (Passer montanus), which is a close relative of the familiar House Sparrow.  Furthermore, they don’t hang out in trees, but are ground-feeding and nesting birds.  In fact, they breed in far northern latitudes on the edge of the tundra where trees are scarce!  Did ornithologists run out of ideas for naming birds?

American Tree Sparrows look like a bigger version of a Chipping Sparrow with their chesnut crown and eyestripe, and the mottled brown and tan plumage.  But they have a faint black spot in the middle of their buffy breast feathers that Chipping Sparrows lack.

american tree sparrow

A small flock of 4 sparrows foraged in the weedy gravel, picking out microscopic (to me) seeds that had fallen there.  I suppose wind-blown seed easily gets trapped in gravel, making it a good place to forage, because the birds spent several minutes scouring the roadbed.

Their plumage camouflages them well in the weedy vegetation.  I didn't even see the bird in the original of this photo until I zoomed in.

Their plumage camouflages them well in the weedy vegetation. I didn’t even see the bird in the original of this photo until I zoomed in.

what is black and white and red..in places?

When we were traveling in Turkey, I got a few chances to photograph some of the wildlife, featured in a recent post, but largely unidentified.  Thanks to one of my savvy fellow travelers who found an image of one of the creatures on Flickr, I now have a name for the caterpillar I saw.  It turns out the species also occurs in the U.S., even in Minnesota, where it was introduced on purpose to control a noxious invasive called leafy spurge. (Below, leafy spurge was one of the earliest plants to emerge last spring near my backyard.)

This little beauty…is the caterpillar of the Spurge Hawk-moth (Hyles euphorbiae), seen in one of its native lands (asian part of Turkey) on one of its natural food sources, perhaps Euphorbia lambii, the Tree Euphorbia.  The plant is native to the Canary Islands, but has been introduced everywhere in the world as an ornamental.

In fact these spurge bushes were crawling with caterpillars, and they were doing a fine job of trimming back the green vegetation to bare sticks.  Black coloration with white spots and red trim makes the caterpillars really stands out.  When streched out, you can see green segments between the black and white.

Typically such eye-catching coloration is a warning to predators that the prey is inedible at the least, or poisonous at the worst.  Its host plants, the euphorb species, are toxic, especially the leaves.  However, sea gulls have been observed to pluck the caterpillars right off the euphorb bushes growing near the sea shore, so perhaps their toxicity is mild.

The adult moth is quite attractive with well-defined brown patches on the forewings and pink coloration on the hind wings.  They are day-flying moths (like other sphinx moths), and exhibit hummingbird-type flight when visiting flowers, hovering near the flower heads and dipping their long coiled proboscis systematically into each flower.

Photo from: http://ukmoths.org.uk/show.php?bf=1986

After mating, females lay clusters of up to 50 eggs on leafy spurge plants, adhering them to the stems with a sticky gum substance.  Easy to see why the plants we saw on our hike were covered with maturing caterpillars.

Photo from: http://en.wikipedia.org/wiki/Hyles_euphorbiae

Even if the caterpillars defoliate the spurge, the plants seem to recover quite nicely.  Unfortunately, the moth’s introduction has not provided the biological control for leafy spurge that was hoped for.

The corn farmer’s bane

We were out for a walk through the prairie a couple of weeks ago, and eldest grandson found a plant with soft, velvety leaves and asked me what it was.  I didn’t know, so he suggested we call it “velvetleaf”.  Well, what do you know, that is its name, because of its chief characteristic — the large, heart-shaped, velvet-textured leaves.

But it is distinctive for its unusual shaped seed pods as well.

Something this odd looking cannot be native, so I looked it up in the Invasive Plant species book, and sure enough, it is a terribly invasive weed, which explains why it was growing so well right at the edge of the prairie in the most disturbed ground.  It is also known as China Jute (for the strong fibers harvested from its woody stem) and Indian Mallow (pretty yellow flowers in the hibiscus family which apparently smell fruity).

(Photo from Wikipedia)

Each seed capsule is multi-compartmented, and each compartment contains 2 or 3 seeds, so each plant can produce a large number of seeds.

And that’s where the bane of the farmer comes into this story.  Velvetleaf is an aggressive invasive in croplands, especially cornfields, and can decrease corn yield more than 30% if left untreated.  Here in the midwest we see lots of TV ads in the summer for various herbicides, and now that I think about it, they all promise to “eradicate velvetleaf”.

But on the prairie, velvetleaf has to compete with native grasses and forbs that cover the ground in a dense mat of vegetation, so it seems relegated to the edge of the fields.

What’s blooming?

The woodland habitat at Snail Lake Park in Shoreview MN is putting on a flower show right now.  What an amazing diversity of colors, shapes, and sizes of flowers I saw on my bike ride today.  A disclaimer for the photos below — I did not take the good camera.  All photos were shot with the little Olympus point and shoot pocket camera, and most of the shots were in fairly deep shade which is challenging for this camera.

Wood sunflowers are everywhere and in great density.

I only saw two of these plants, both of which just had 1-2 open flowers.  I am calling it a blue aster, but don’t think that is quite right.

This is White Campion or White Cockle, which has separate male and female flowers.  The male flowers have a more tubular flower shape with stamens in the center of the petals (lacking female parts), and the female flowers have the more swollen shape, like the one you see in the extreme right corner of the photo, and lack stamens.

Canda Thistle prefers habitat with more light, and this plant was about 7 feet tall where it was growing in semi-shade.

I think this is Canda (or Showy) Tick Trefoil, a member of the bean family.  Pairs of Japanese Beetles were mating all up and down the stems, but seemed to leave the flowers alone.

Purple (but it looks pink here) Loosestrife looks a lot like the Tick Trefoil, but it has smaller flowers in tighter clumps, and they have 5 regular petals instead of the pea- or bean-shaped flower that has a banner (top), two wings, and a keel.  Honeybees and bumblebees love this plant.  Wetland enthusiasts hate this plant because it is too successful and displaces all kinds of native aquatic vegetation, even cattails.

Another introduced plant wreaking havoc in both gardens and crop fields is Creeping Bellflower, which spreads into a thick mat if left undisturbed.  It propagates really well from an underground rhizome and can even successfully invade grassy lawns.

The Common Evening Primrose can grow  4-5 feet tall, but typically has just a couple of flowers open at any one time.  They only last about a day, opening in the evening (hence the name!) and fading by the next afternoon.  Under UV light exposure the petals exhibit a striped pattern that pollinators follow to the nectar source.

Joe Pye Weed grows in dense clumps, and the flower heads look fuzzy with their highly dissected petals standing upright.  Who is Joe Pye that he got a plant named after him you might wonder?  He was a Native American physician who used plants medicinally in  his New England practice.  The Ojibwe Indians used this plant to make “strengthening baths”.

Canada Goldenrod grows better in full sun, but it was abundant in the semi-shaded habitat as well.  Most of it looked perfectly normal, but some of it had stunted stems with fuzzy tops and no flowers. The New Hampshire Gardener blog explains that this aberrant growth form is due to the Goldenrod Midge which lays its eggs in the leaf bud, causing a “bunch” of leaves to form in place of the normal flower stalk.

Hedge Bindweed  is a perennial twining vine member of the Morning Glory family that can grow up to 10 feet long.  With its rapid growth and climbing habit, it can quickly overgrow and overwhelm small herbaceous plants and is considered a nuisance.  The flowers are pretty though.

Spotted Touch-me-not (sometimes called Jewelweed) has single flowers that hang delicately beneath a leaf.  The ripe seed pods expand with gas and explode when touched, spraying seeds into the nearby vicinity.  Another fun activity for kids on a late summer walk…

The last plant in today’s photo collection is White Snakeroot, a very common, shade-loving, noxious perennial that is poisonous to livestock.  Not only does it cause lethargy, excessive salivation, muscle weakness and breathing problems in horse, sheep, and cattle, but the tremetol poison is passed into the milk and can incapacitate and kill humans who drink the tainted milk (“milk fever”).  Supposedly this is the cause of death for Abraham Lincoln’s own mother.  So don’t let your livestock, pets, or children eat this.

Skippers

What are they?  A large family of small butterflies that all look alike.  Fortunately, here in the Northland, we have fewer Skipper species to try to identify.

The name Skippers refers to their darting flight pattern, primarily in and out of low, grassy vegetation.  This large family of 3000+ species worldwide falls into three groups based on how they position their wings at rest.  The spreadwing group rests with wings flat, the grass skippers rest with wings folded, or just the hindwings extended, making them extra hard to ID, and the third group is intermediate between the other two.

Arctic Skippers fall into this third category, but are easily identified by their striking checkered pattern and less than completely outstretched wings.  I came upon this little (less than an inch) butterfly flitting through the Ground Ivy (Creeping Charlie in the US) in late May, and the bright coloration immediately caught my eye.

In addition to the checkerspots on the dorsal (top) side of the wings, this butterfly has silvery spots on the underside of the wings that stand out when its wings are folded.  They are found in northern latittudes around the world, breed early in the spring, and raise just one brood of caterpillars, which pupate in late summer and overwinter in their chrysalis.  Ecobirder has more information and good photos of this butterfly.

Currently, a different skipper species is abundant in the low grasses around the pond iin the backyard.  I think I saw about 50 of them today.  This is the Least Skipper, a member of the grass skipper group which typically rests with both sets of wings folded, or just the hind wing extended while the forewing remains folded vertically.  They have a solid orange underwing coloration, and orange with black border on the dorsal surface of the forewing, somewhat similar to the coloration of the introduced European Skipper.  Their tiny size (about one-half inch) and darting flight might make them hard to catch.

Skippers are interesting looking because they have very large eyes, fuzzy hair-like insulation on their thorax and abdomen, and exceptionally long proboscis feeding tube, which, when extended its full length, can be longer than their body.  The caterpillars are nocturnal feeders, which might explain their larger eyes, but the adults feed in the daytime, so it’s not clear why they have the extra insulation or the larger visual apparatus.

One advantage of such a long proboscis is that the butterfly can stand in one spot and probe dozens of flowers in a compound flowerhead.  Some researchers have hypothesized that many butterfly species are nectar thieves rather than true pollinators, like bees, because they stand on the outside of a flower and can reach the nectaries with their long proboscis without contacting the male or female flower anatomy.  In support of this idea, they have documented low pollen transport by these butterflies.  In the photo below, the proboscis of the skipper is the thin brown tube extending straight out from its body at about 45 degrees.  It seems to be at least as long as the butterfly is.