June 20, 2010

ORIOLE AT BREAKFAST
Most mornings this week at about the same time each day, just before the sun came up but when already there was enough light to see things, a certain oriole has visited as I sat beside my hut's door eating breakfast. On the first morning he landed not ten feet from me and very plainly looked me over, first with the eye on one side of his face, then with the other, then he changed perches and did it all over again, then practically he hung upside down looking, then he flew closer, onto the ground, then onto a rock... and then he flew off. You can see him on the ground at https://www.backyardnature.net/n/10/100620or.jpg.

On subsequent visits his gawking was hardly less obtrusive; on Friday he arrived with his father, who behaved the same. Visits seldom last for more than a minute.

They're Black-cowled Orioles, ICTERUS DOMINICENSIS, and the one in the picture is immature. You might remember that last December we saw a male Black-cowled, presumably this one's father, fighting himself in the mirror of a car in the parking lot. That story and a picture of the father at the mirror is at https://www.backyardnature.net/yucatan/bc-oriol.htm.

I see several orioles each day. Usually they're the big, frequently-calling Altamiras, but also Hoodeds are common here. Black-cowled Orioles just show up from time to time, and when I do see one often it's that male still attacking his image in various car side-mirrors. I've not seen other orioles do this, nor have the immatures of other oriole species made such gawking visits to me. I'm getting the notion that this species tends to have some quirky behavior.

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A WANDERING SMUDGE OF LOCUST NYMPHS
Late Monday afternoon I was reading beside the hut door when my peripheral vision caught movement beyond the book's page. When I looked up it took a few seconds to figure out what I was seeing. It was a black smudge of grasshoppers advancing like a platoon of soldiers across the ground toward my potted basil. You can see them, 35-40 of them walking and hopping, at https://www.backyardnature.net/n/10/100620lo.jpg.

You can see two of them advancing in their rather clumsy-seeming manner, their oversized back legs keeping them from achieving a smooth stride, at https://www.backyardnature.net/n/10/100620lp.jpg.

Actually I'm not sure whether to call these grasshoppers or locusts. Basically, locusts are just grasshoppers in large numbers. Hormonal and physical changes occur when typical solitary grasshoppers become locusts. Often one change is that the locust becomes more brightly colored than the grasshopper. But I'm not sure whether 35-40 grasshoppers moving en masse qualify as locusts. Because of their definite group movement toward my potted basil, and their bright colors, I'm calling these locusts until someone corrects me.

I'd been growing those pots of basil a long time so I got up and moved them. However, also I wanted to see what the locusts would do when they found a plant. Some climbed the Chaya plant next to my hut -- recently defoliated during a caterpillar outbreak -- and you can see two of them nibbling new Chaya leaves at https://www.backyardnature.net/n/10/100620lr.jpg.

In that picture notice that the insects' wings are only about a third developed. These are not mature grasshoppers or locusts, but rather nymphs. Grasshoppers undergo incomplete metamorphosis so there's no caterpillar or pupa stage between the egg and adult. A tiny edition of the adult emerges from the egg, then undergoes a series of molts, enlarging after each molt, until the adult is formed. Younger, smaller nymphs have no wings, but with each molt the wings more fully develop. So, these are late-edition nymphs with wings, but the wings are too small for flying.

I picked up a nymph and you can see its head at https://www.backyardnature.net/n/10/100620lq.jpg.

As soon as I disturbed that individual it began disgorging a bubble of plant juice, so apparently it had already fed.

Earlier, when I'd approached the smudge, individuals had hopped in all directions, most eventually finding some kind of plant to chew on. After about ten minutes, though, each seemed to lose interest, crawled back onto the ground, and then from all directions individual grasshoppers/locusts began leaving my general area. Three or four in a tight, dark cluster were heading toward the Hacienda Office, and all others appeared to be half-walking, half-hopping in their general direction, slowly enlarging the group as they went.

I've described and photographed some enormous locust outbreaks here in the Yucatan. Those accounts are at https://www.backyardnature.net/yucatan/locusts.htm.

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BLACK WITCH
Six-inch-across (15 cm), dark moths have begun spending their days in my hut, their big wings flush with the ceiling's thatch, or maybe they'll be on my pole walls or the vine door, or even outside beneath the thatch overhang. You can see one on the vine door at https://www.backyardnature.net/n/10/100620wi.jpg.

I sent volunteer insect identifier Bea in Ontario a picture and it wasn't long before a message came back telling me that I was in for a heap of trouble. What we have here is the Black Witch Moth, ASCALAPHA ODORATA, a species familiar to country folks from Brazil through Central America, Mexico and the Caribbean, and sporadically deep into the US. And any hut-dwelling country person in that vast range will tell you: Having a Black Witch in your hut is not good news. If someone in your hut is sick and a Black Witch enters, the sick person will die. In Mexico Black Witches commonly are called Mariposas de la Muerte, or Butterflies of Death. In Maya a Black Witch is Mahá-nahí, which roughly translates to a less menacing "House Borrower."

At https://www.backyardnature.net/n/10/100620wj.jpg a close-up of a Black Witch's head shows a bulbous, black, many-windowed compound eye and a brownish, coiled proboscis. Many large, showy moths live so briefly that they possess no mouthparts -- they only live long enough to mate and lay eggs. But you can see from our moth's frayed wing margins that Black Witches live awhile. The proboscis enables the adult to eat soft, mushy or rotting fruit, sugary tree sap and the like. Caterpillars feed on the leaves of trees and shrubs in the abundant Bean Family.

Of course my Maya friends assure me that the bit about the hut's occupant dying is purely a superstition. What bothers me is the way they tell me -- a little too gaily, a smile a little too forced, a voice a little too encouraging, the way you talk to someone whose doctor has given them only days to live.

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BLOMFILD'S BEAUTY
I've been here for seven months and during that time I don't believe I ever saw the pretty butterfly shown at https://www.backyardnature.net/n/10/100620bb.jpg.

A side view showing a much different pattern is seen at https://www.backyardnature.net/n/10/100620bc.jpg.

Noticing how big-headed, thick-bodied butterfly avoided holding its wings completely horizontally, I thought that maybe it was an unusually colorful skipper. However, Bea in Ontario pointed out that the antennae aren't hooked like those of skippers she's seen, so she didn't even bother looking among the skippers.

It's a male Blomfild's Beauty, SMYRNA BLOMFILDIA, a member of the huge Brush-footed Butterfly Family, the Nymphalidae, closely related to the North's Admirals. The species feeds on Urera trees, stinging members of the Nettle Family, and we have lots of Ureras here, which we called Cow-Itch. We look at them at https://www.backyardnature.net/yucatan/cow-itch.htm.

Adult Blomfild's Beauties feed on rotting fruit, which explains why they can't stay away from the mango peels on my compost heap. The species is distributed from Peru through Central America and Mexico, wandering periodically into southern Texas where butterfly watchers regard it as a great sighting.

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A GOOFY-LOOKING CUTWORM
During the organic garden's first weeks the prize plant was a lusty zucchini seeming to promise all the harvest we needed, just from it. But then a couple of weeks ago it stopped growing, the edges of its expanding leaves turned brown and crisp, the whole plant grew anemic looking, and clearly something was wrong. Finally this week I couldn't stand looking at its wretchedness any longer, pulled it up and, suspecting what the problem was, twisted its brittle stem until it split. The problem is shown at https://www.backyardnature.net/n/10/100620cw.jpg.

It was the dreaded Squash Vine Borer, MELITTIA CUCURBITAE. I've run into this critter before but when I got the above picture on the screen I was surprised by some of the grub's features.

First, the grub has the rudiments of a regular caterpillar's tiny feet. Second, the head at the top looks like it's equipped with two beady, brown little eyes. Similar brown dots appear along the grub's sides and I assume that they are spiracles -- breathing holes. But those "eyes" on the head left me wondering. For, regular caterpillars have large compound eyes consisting of hundreds or thousands of little windows. They just don't have beady, brown eyes like these. And even if they were beady, brown eyes, of what use would they be inside the stem?

On the very day I took that picture, Eric in New York sent me an article from The New York Times.  That article is about caterpillars with "false eyes" that cause the caterpillar to look like it's staring at any potential predator. So maybe that's what's going on here.

But, still the question remains as to what use such false eyes might be in the darkness inside a squash stem. Do some predators break open squash stems looking for grubs? If they do, would the face displayed on our zucchini grub scare them away? At least to me, the eyes just make the grub look goofy, but maybe a stem-slashing bird would feel different.

It's hard to control stem borers in an organic garden, basically because once they're inside the stem they're pretty well protected. If you can figure out the grub's location in the stem, maybe by spotting frass (poop) at little holes in the stem, the stem can be cut open lengthwise and the grub picked out. Where borer outbreaks are really bad, nylon stockings or aluminum foil can be wrapped over a vine's lower stems. Another trick is to cover the squash vine's stem at various points with soil, encouraging rooting, so that if a lower part of the stem gets destroyed, roots at the upper part can take over.

But, in practice, these measures are a bit awkward to use. Stem borers are just a real problem. My main technique against them is to put out many more plants than I expect to need, and scatter them, hoping that if some get zapped in one place, others may survive in others.

*****

TADPOLE UPDATE
In the May 23 Newsletter I showed you frog eggs in one of our reflecting pools, and the week after that we saw the resulting very numerous tadpoles. They still are showing no signs of legs, but now a month later other important changes can be noted.

The main visual difference is that the tadpoles are bigger, and there are much fewer of them. I know from reading that right now massive changes are occurring inside their bodies, especially as their long, slender, vegetarian guts change to the short, thick guts needed by insect-eating adult frogs. A question I've wondered about was whether, as the tadpoles grew more froglike, they might start eating one another...

This week I thought I was seeing tadpole cannibalism when I snapped the shot shown at https://www.backyardnature.net/n/10/100620tp.jpg.

At first it looked like a tadpole was nibbling on the body of a dead, tailless tadpole, but once the image was on my laptop screen it looked more like it was feeding on white, filamentous fungus emerging from the dead tadpole's body; it's hard to say. The nibbler was certainly nibbling very aggressively for several minutes, though.

On the Internet I read this: "The role of tadpoles in aquatic systems is gradually being redefined, with recognition of their importance as carnivores and scavengers rather than strict herbivores and detritivores." A tadpole study's abstract is online at http://eco.confex.com/eco/2007/techprogram/P3707.HTM.

Maybe a raccoon or similar animal decimated the pool's tadpole population, or maybe most of them died one night when the high algae concentration removed so much of the water's oxygen that the tadpoles died of asphyxiation. Or maybe now that the pool's tadpoles are getting their short, thick guts in place, they're starting to eat one another...

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FOXTAIL GRASS
Though no trees, bushes, vines or wildflowers found here are species that also occur in my usual haunts up North, some weeds here are indeed the same species. Other weeds look more or less the same, but they turn out to be different species. Therefore, with weeds I'm seldom sure whether I'm seeing an old acquaintance or something entirely new for me. I just have to go through the identification process and see if I end up with a species known to occur in the US.

The other day as I hiked to Pisté to buy fruit, at the edge of the concrete sidewalk connecting Pisté and the ruins' entrance, I saw some foxtail grass that looked like a species I knew back in the US Southeast. Foxtail grass, genus Setaria, is an easy-to-recognize grass genus because its tiny flowers are arranged in spike-like panicles (the "fox tails") atop the grass's stem. Also, long, stiff, hairlike bristles arise below each foxtail flower. Several foxtails beside the sidewalk between Pisté and the ruins are shown at https://www.backyardnature.net/n/10/100620fx.jpg.

At https://www.backyardnature.net/n/10/100620fy.jpg a close-up shows individual, egg-shaped flowers along one side of a foxtail's spike-like panicle. Each ovate flower is topped by the dry, brown remnants of old, feathery stigmas and anthers. The lowest flower is pale straw-color because it's mature and ready to fall off. At the lower left notice the small peglike items, like thick-based golf Tees. The pale, round surfaces are scars from other mature flowers that already have fallen off their flower stems, or pedicels. Below one such pedicel scar you can see that maybe eight stiff, hairlike bristles arise.

When you identify foxtail grasses you need to count the bristles because bristle number per flower varies from species to species. Also, some foxtails are annual with fibrous roots while others are perennials with rhizomes. Ours have rhizomes with curiously knotty nodes along the length, as shown at https://www.backyardnature.net/n/10/100620fz.jpg.

So, eight or so bristles per flower, a shortish inflorescence about two inches long (5 cm), and being a perennial with a knotty rhizome -- that makes this Perennial Foxtail-grass, SETARIA PARVIFLORA, sometimes also known as Setaria geniculata. It's common in many places and goes by several English names, especially Yellow Foxtail, Perennial Foxtail and Knotroot Bristle Grass. It grows in marshes, ditches, moist disturbed areas and the like in much of the world, especially the tropics, where it's a weed. Apparently it's native here.

So, in this case the weed looked familiar because I've run across it up North. Next time I hike to Pisté for bananas I'll give it the nod due an old acquaintance.

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CLOCKWISE & COUNTERCLOCKWISE TENDRILS
On my first full-fledged botanical expedition, in 1974 or thereabouts, on an overnight Varig flight from New York to Brazil, I knew exactly the first thing I wanted to do upon passing customs in Río de Janeiro: I wanted to make a beeline into a bathroom and flush a commode to see if, because of the Coriolis Effect, the water drained out clockwise, as it's supposed to north of the Equator, or counterclockwise, as I'd always read it does south of the Equator. Result: it drained straight down without spiraling. Eventually I found that some flushes south of the Equator went "right," others "left," so I was a little disappointed. There's an in-depth look at this whole issue at http://www.snopes.com/science/coriolis.asp.

Despite those disappointing results, wherever in the world I've been since then, I've halfheartedly tried to figure out whether vines and their tendrils take the Coriolis Effect into account. Maybe because during most of my travels I've been too hot or too cold, too hungry or too sick, too lost or too sleepy to think straight, somehow my whole life has passed without my figuring it out. Therefore, this week in the organic garden I was transfixed when I saw what's shown at https://www.backyardnature.net/n/10/100620cu.jpg.

That's a cucumber tendril. It originated on a vine beyond the picture to the left, coiling clockwise, then it changed direction and began coiling counterclockwise, then after three cycles it changed directions once again to clockwise, and by golly it looks like that as it's wrapping itself around the vertical pole, it's doing so counterclockwise.

On the Internet, there are answers to questions such as what's going on with cucumber vine tendrils.

The fast answer is that science doesn't really know what causes plants and their tendrils to wrap one way or another around a pole. Most vines twine counterclockwise, though about 10% go clockwise. Some do it both ways. The twining direction of vines is not dependent on whether the plant lives north or south of the Equator. Twining direction is genetic, and some species go one way while others go the other.

And cucumber vines, they say, and as we've seen ourselves, can have tendrils coiling in either direction.

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CYCLES, CUCKOO CLOCKS & BLOSSOMINGS
Here we've heard predictions that this summer the Yucatán will have much more hurricane activity than normal. Each day I check various websites that locate and analyze current tropical depressions, storms and hurricanes. If we're going to have a hurricane, I plan to experience it from beginning to end.

Among my favorite storm-watching sites is one with animated satellite images of the Caribbean's weather patterns, great for watching hurricanes approach, at http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html.

All the planet's tropical storms are located on a map and discussed, with links to technical terms, at http://www.wunderground.com/tropical/.

In a discussion of a tropical depression that worked its way across the Atlantic toward us this week, at the above link they wrote that "... the Madden-Julian Oscillation is currently favoring upward motion over eastern tropical Atlantic, and this enhanced upward motion helps create stronger updrafts and higher chances of tropical cyclone development." After looking it up I learned that the Madden-Julian Oscillation is a traveling, repetitive weather pattern consisting of large regions of tropical rainfall of either above or below average.

With the Summer Solstice taking place tomorrow, and my being in the Maya culture whose traditional calendar conceives of cycles within cycles, lately I've been thinking a lot about cycles, and now here's another one, this Madden-Julian Oscillation.

Tomorrow's solstice, though, because it's part of a cycle affecting how solar energy is distributed across the Earth's biosphere, deserves more attention than most recurring events we celebrate. The cycle commemorated tomorrow not only meshes with untold numbers of other cycles, but its cyclic nature encourages life's evolution to ever higher states. (In general, biological evolution proceeds faster in disrupted systems than static ones.) Tomorrow's solstice is less like the return of a cuckoo-clock's cog to an earlier position, than it is an important milestone during a gorgeous blossoming.

So, this: A flower in empty space detonating into existence -- bright corolla, sweet fragrance, its prime motive of sexual energy usurping dead nothingness with sheer voluptuous presence and vitality... with us inside that blossom vividly aware of where we are, and exulting in the experience...

That mental image is the gift to those who celebrate tomorrow's Summer Solstice.

An explanation of what's going on tomorrow is at http://geography.about.com/od/physicalgeography/a/summersolstice.htm.

*****

Best wishes to all Newsletter readers,

Jim