Saddleback bites the dust

Not long ago, I was delighted to come across a small redbud tree filled with caterpillars. There were at least five species noshing away, including three saddleback caterpillars, Acharia stimulea. Saddlebacks grow up to be rather ordinary little brown moths, but they're truly spectacular as larvae. It's as if a sea slug was saddled with a tiny lime-green horse blanket.

However, I noticed that the individual in these photos was not looking especially lively. Even though the caterpillar looked pretty good - slightly faded, perhaps - something was amiss. So in we go for a closer inspection.

Uh oh. While making macro photos - those little columns of spines will give you one heckuva sting by the way - I noticed a major problem for the poor little cat. That tiny white cylindrical object is an egg from a tachinid fly. These bristle-bodied parasitoid flies are among a caterpillar's worst nightmares. In this case, I think that's probably the old case of the egg - as we shall see, it looks as if the fly has already spun its gruesome magic.

Tachinid flies, which rather resemble house flies, are major caterpillar predators and attack the cats by sticking an egg to the the larva's exterior. In short order, the fly grub hatches from the egg and bores directly through the caterpillar's skin and into its interior.

Once within the caterpillar, the ever-growing fly grub begins consuming non-vital hemolymph fluids and tissue. Clever parasitoids that they are, it would not behoove the grub to kill its victim until the last possible moment, as a living host is better able to move about and better avoid other predators such as birds. In a final frenzy, the fly grub goes ape and eats all of the innards before bursting from the caterpillar and going off to pupate.

In this photo, we can clearly see what must be the grub's exit hole. What a show that must have been, and I'm sure you wish I had caught the grub bursting from the caterpillar's husk on video so you could enjoy that bit of cinematic loveliness as you ate your breakfast. But such a video was not to be - I suspect that these tachinid fly grubs tend to emerge under cover of darkness.

As I was making these photos, this tiny chalcid wasp alit on the caterpillar husk and began looking around. This little wasp is looking to parasitize the fly by laying eggs on either the fly grub or its puparium. The world of parasites and parasitoids (the latter generally kill their hosts) is truly strange and multidimensional.

I made this photo a few weeks ago. While photographing this caterpillar - a yellow bear, Spilosoma virginica, I believe - I noticed a tachinid fly perched nearby. The fly watched the bristly caterpillar's every move, occasionally shifting position to get other viewing angles. Yellow bears are heavily beset with stiff hairs, and the fly was undoubtedly waiting for an opportune moment to get at some unprotected part of the caterpillar. I watched for a while, but had to leave before the fly moved in. I wish I had had the time to stick around and film the actual attack.

Nashville Warbler

There has been a good movement of warblers through central Ohio the past few days. Lots of diversity, and decent numbers of many species. This'll be our last substantial pulse of migrant warblers for the year. Come the second week in October there is typically a marked dropoff in most species.

Sparked by various reports today, I ran out for a brief visit to our little habitat patch in urban Columbus, just outside my office. In no time, I saw American Redstart, Common Yellowthroat, and the above, a Nashville Warbler, Oreothlypis rufacapilla.

Nashvilles have a suite of three instantly noticeable characters: gray head, yellow underparts including the throat, and a bold white eye ring. The latter field mark sometimes causes them to be confused with a much rarer and altogether different beast, the Connecticut Warbler. In fact, I heard reports of as many as a half-dozen Connecticuts at a local park today. Hmmmm...

Anyway, this bird's distinctly Tennesseean name stems from the Father of Ornithology himself, Alexander Wilson, who first collected this species near Nashville in 1811. It's not a very descriptive name, as Nashville Warblers don't breed anywhere near the Volunteer State - it is primarily a bird of boreal forest zones in the northern U.S. and Canada. They prefer scrubby successional growth as nesters, and this is THE common warbler in the young jack pine colonies where Kirtland's Warblers breed.

Nashville Warblers have a fascinating breeding distribution. There are the eastern birds, such as in my photos. And then there is the western "Calaveras Warbler", as it was once called. This western population breeds in the far northwestern U.S. and adjacent Canada, and is widely separated from the eastern breeding population. The westerners are given subspecific recognition: Oreothlypis rufacapilla ridgwayi. The trinomial ridgwayi recognizes ornithologist Robert Ridgway, who first found the "Calaveras Warbler" in Nevada in 1868.

The majority of Nashville Warblers travel to central and southern Mexico for the winter, and that's probably where this bird will end up in a few weeks. Today, though, he gleaned insects from our box-elder trees and brightened my afternoon.

Zombie fungus

If I've said this once, I've said it 100 times: If you are a reincarnationist and believe you have any control over your destiny, DO NOT come back as a bug! Nearly everyone and everything will be out to get you, and the end can come in gruesome ways that even Hollywood horror flick producers haven't dreamed up. Graphic evidence as to the folly of life as an insect follows; an especially apropos example as we near the Halloween season

On a recent excursion to Adams County, I spotted this cricket high on a leaf. Its identification flummoxed me. It looked like a camel cricket, but an utterly bizarre specimen, and one normally wouldn't find crevice-loving troglodytean camel crickets climbing high on leaves in the forest understory. A closer inspection revealed that I was looking at the dead husk of the cricket - it had fallen victim to some seemingly terrible fate.

So I sent a photo off to orthopteran expert Wil Hershberger and soon had my answer. Zombie Fungus! I was correct in that it was a camel cricket, and a female as evidenced by that long scimitar-shaped ovipositor jutting from her rear. But I couldn't square all of the bristles or spines with anything that I was familiar with.

In a nutshell, here's the story and its a horrorshow. Apparently there are numerous species of fungi, many or most in the genus Cordyceps or closely allied genera, that attack various insects. Ants, wasps, and crickets seem to be common victims. When spores of the fungus land on an unlucky but suitable host, they then germinate and the fungus invades the interior of the animal via its spiracles, or air holes that allow respiration. Once inside the victim, the fungus grows rapidly by sending out tentacles known as mycelia, which radiate throughout the victim's innards. These fungal tentacles begin consuming the insect from the inside, but the fungus cleverly avoids ingesting the most vital organs. By prioritizing its consumption of the insect's inner workings, the fungus keeps the victim alive and mobile.

When the alien invader has ingested enough mourishment from its host and grown to unstoppable dimensions, its snakes more of its mycelia into the creature's brain. Then things get really whacky. Somehow, the zombie fungus is able to produce specialized chemicals that alter the insect's perception of pheremones - the chemical codes that many insects produce that guide them to prospective mates or otherwise dictate behavior. The zombie fungus somehow remaps the (in this case) cricket's sensory perception to such a degree that the animal behaves differently than it normally would. Hence, my discovery of this camel cricket in a site where it would not normally be.

Once the zombie fungus has manipulated its host into a site that allows for maximum spore dispersal, it commences its grisly last hurrah. Now that the victim is properly positioned and its brain functions and motor skills are no longer required, the fungus launches an all-out feeding frenzy, consuming the brain and other vital internal cogs. In a horrific grand finale, the zombie fungus shoots forth long slender stalks from the victim's body - the "bristles" that we see in my photos. Fungal spores are released from the summits of these stalks, and drift off to start the cycle over.

I am personally rather grateful that these zombie fungi have not yet made the jump to human hosts, at least insofar as I am aware. They might someday, though. You'll know they have when you spot a person who has scaled to the summit of a flag pole, and long tentacle-like bristles are waving from his hollowed out body.

Sky-blue Aster

Sky blue aster adds appealing hue to fall

COLUMBUS DISPATCH

Jim McCormac

October 2, 2011

NATURE

Asters are one of fall’s signature plant groups. More than 30 species native to Ohio tint our woods and fields with blues, purples and whites, providing lively punctuation to the browning of autumn.

The ornate flowers seem magical — and perhaps they are. The ancient Greek goddess Astraea, associated with the constellation Virgo, flung stardust to the Earth, and asters sprung up wherever the celestial particles struck. A less fanciful explanation is that the aster family (Asteraceae) — the world’s largest vascular plant family with almost 23,000 species — has evolved with extraordinary success.

Back in the Wild West days of botanical exploration, a Renaissance man named John Leonard Riddell spent time in central Ohio. He was a roving lecturer, physician, geologist, chemist and politician. He even wrote a science-fiction book about space travel. But, above all, Riddell is immortalized for his work as a botanist.

Riddell’s travels took place at a time when new discoveries were routine, and the Ohio frontier was not yet well-documented. He was among the first botanists to step foot in the largely unexplored habitats that cloaked the core of Ohio. One of his finds bears our state’s name: Ohio goldenrod.

But even Riddell, used to new discoveries, must have been elated one fine September day as he investigated the bluffs over the Olentangy River near Worthington. Looking down, he saw a plant bearing panicles of stunning azure flowers, as if its branches held galaxies of starry blossoms. Riddell had found what would become known as sky blue aster, and he named the plant for the river where he found it: Aster oolentangiensis (now Symphyotrichum oolentangiense).

Sky blue aster is a standout in a pageant of botanical beauties. All of the blue-flowered asters are knockouts, but Riddell’s find is hard to match. A healthy plant can tower 3 feet or taller and sport dozens of deep blue flowers. Such a specimen would draw oohs and aahs if planted in a sophisticated gardener’s bed.

Naturalist Jim McCormac writes a column for The Dispatch the first and third Sundays of the month. He also writes about nature at jimmccormac.blogspot.com.

Field Sparrow

I had the opportunity to hang out a bit with members of the Ohio Bird Banding Association at their fall meeting, last Saturday morning. Unfortunately, the day dawned cold, drizzly and dreary, and the inclement weather impacted our ability to capture birds. Nonetheless, a few songbirds found their way into the nets, including one of my favorite sparrows.

A long string of nets stretches through an old field of goldenrod and aster at Hopewell Culture National Park near Chillicothe, Ohio. This can be a great locale for sparrows, and a few years back we netted about seven Henslow's Sparrows in this very field. Such success wasn't to be on this day, though. Part of the problem was the physical conditions. The best way to up the successful capture rate of sparrows is to line people up and organize drives through the field, herding the birds towards the nets. When those four foot tall matted tangles of goldenrod are saturated with rainwater, it's a tough task to trudge through them, and the driver will emerge soaked from the waist down. Plus, banders must of course put the birds' health and well-being first, and when conditions become too wet and chilly its best to roll up the nets and wait for a better day.

When conditions permitted, a few birds were caught. Here, bander Kelly Williams-Sieg removes a Field Sparrow, Spizella pusilla, that became entangled in the net.

And here he/she is, posing for us. This is a hatch-year field sparrow, sex unknown. Determining whether some young songbirds are boys or girls is not always easy, or possible.

Three major field marks can clearly be seen on our bird. It has a rusty cap, pinkish bill, and prominent white eye ring. Those three characters should serve to separate it from any other sparrow that you'll see in these parts. Young White-crowned Sparrows can suggest a Field Sparrow, but they are proportionately much larger and bulkier, among other differences.

One reason I like these dapper little sparrows so much is due to their lovely melodious song. This is how I described it in my book, Birds of Ohio: "...an accelerating series of short liquid whistles, sounding like a table-tennis ball dropped on a table and bouncing to a stop". That's hardly a unique or innovative song description, I realize, but it does pretty much sum up the sound.

The tune of the Field Sparrow is still a pretty common sound in Ohio, but the bird is declining. All manner of rampant development coupled with neater, cleaner agricultural practices have cut way down on the amount of suitable habitat. Partners in Flight estimates that 460,000 of these little songsters still make their home in Ohio, though.

The Field Sparrow above was born last summer in a well hidden grassy condo such as above. I found this nest a few years back in a grassy field, and the nest's opening is dead center in the photograph. Without benefit of seeing the parents making visits to the nest, it is highly unlikely it would be spotted. I saw one of the adults come out of that tussock and knew a nest would be close at hand, and with a bit of careful searching found it.

Moving in for a closer view, we see that baby Field Sparrows are born into a soft, grass-lined cup carefully crafted by the parents, and well secreted. Brown-headed Cowbirds can be good at spotting these nests, though, and female cowbirds regularly dump eggs in Field Sparrow nests. However, this species of sparrow can recognize the intruder's egg, but alas, the diminutive little Field Sparrow usually lacks the brute force required to shove the egg from the nest.

So, the sparrows often just pack their bags, abandon the nest, and build a new one elsewhere in the field. If cowbirds plague them once again, they might start the whole process over yet again. There are instances where long-suffering Field Sparrows have built and rejected numerous cowbird-parasitized nests.

But if all goes well, the world is graced with another beautiful little pink-billed sparrow, and the bouncing pingpong ball song will once again echo delicately from our meadows.

Carolina mantis

A female Carolina mantis, Stagmomantis carolina, stares inquisitively at your blogger. I had the good fortune to find several of these charming native mantids in southern Ohio last weekend.

A short while back, I wrote about the non-native Chinese Mantis, HERE. One tends to see far more of those than the much more diminutive native Carolina mantids. I have heard it postulated that the larger more aggressive introduced mantids will displace their native brethren. Could be; I certainly see few of the Carolinas and scads of the Chinese.

Carolinas are much smaller than the Chinese mantids; perhaps half that size. They're also a pleasing gray color, dusted and dappled with ashy blotching.

Here's a different female Carolina mantis, found the same day as the one in the first photo. It has been my observation that this species tends to be quite arboreal and I've found most of my specimens in the low hanging foliage of trees.

I believe the one above is gravid, judging by her swollen abdomen. Hopefully her mate made it out alive. Some estimates have it that up to one-quarter of males perish shortly after consummating their relationship with the female. The smaller, weaker male is set upon, and eaten by the cannabalistic female mantis. I don't like that, personally. I find it rather rude.

Cylindrical objets d' art

I'll get off the catepillar jag after this post, promise! But I've become smitten with everything about caterpillars: their appearance, behavior, interaction with plants and predators, and overall ecological importance. As a field of study, they are exquisite and provide endless intellectual stimulation.

And as a photographic subject, caterpillars are nearly without parallel in the insect world. They embody everything that I like about shooting nature. There is very much the element of the hunt involved, and that requires some fairly detailed knowledge of the quarry. How many caterpillars do you see when you are out hiking about? One must train their eye to find them. Also, objects that are long and cylindrical can be surprisingly hard to photograph well. Some thought must be given to the pose, and the photographer must make the effort to put themselves in odd positions to fire from interesting angles.

Looking straight on at a banded tussock moth caterpillar, Halysidota tessellaris. It resembles a fuzzy pipecleaner decked out with long, ornate lashes. And sporting a walrus mustache, to boot.

Here's the animal in its entirety. This one was feeding on the foliage of redbud, Cercis canadensis. Banded tussocks are very common caterpillars in the eastern U.S.

Looking like some bizarre and spooky alien from outer space, an irate white-dotted prominent caterpillar, Nadata gibbosa, lunges from the leaf of a post oak, Quercus stellata. I ticked off the animal by tapping it, and this posture is its last ditch effort to ward off the would-be predator. The caterpillar extends and bares its colorful mandibles to create the illusion of scary eyes, and thrashes and lunges. Were you a small animal such a bay-breasted warbler, you might well be inclined to leave the thing alone and search out less intimidating prey.

This is the same white-dotted prominent before I irritated it, peacefully snacking on oak leaves and not looking very dangerous.

The hidden world of caterpillars is indeed a strange and interesting place. I'll tip you now to an event that you won't want to miss. Next year's Midwest Native Plant Conference features Dr. David Wagner as the keynote speaker. Dave is author of the incredible guide, Caterpillars of Eastern North America and he's an incredible and engaging speaker. We'll also be conducting evening field trips to search out cool cats such as the ones in this post, and many more. CLICK HERE for conference details and block it off on next year's calendar.