December 11, 2011

WASPS VS ANTS
When I arrived back at the hut about five weeks ago a new resident in the neighborhood nested in the hut's roof thatch about four feet east of the door, as seen at https://www.backyardnature.net/n/11/111211wv.jpg.

This looks like the same wasp species we've chronicled before nesting in trees. You can see inside a nest at https://www.backyardnature.net/yucatan/paperwas.htm.

Upon my arrival the wasps were constructing the interior combs in which they'd raise their brood, but soon they began covering the combs with their coarse, gray paper made from chewed wood pulp. I watched the nest slowly take form day after day. You can see some wasps milling about their finished nest entrance at https://www.backyardnature.net/n/11/111211ww.jpg.

The wasps, which can deliver a moderately painful sting, never bothered me, always letting me stand close and watch, only occasionally darting at my face if I got too close, not stinging. The Maya, who accuse most reptiles and arthropods of every kind of devious and malicious intent to injury, admit that these wasps, which frequently live in their own hut thatch, hardly ever sting a hut's occupants. They say the wasps learn the hut owner's scent, and that only visitors need to take care.

And then about midday one day this week I returned to the hut to find a cloud of wasps buzzing around the nest, while on a Tree Cotton bush directly before the nest hundreds of them clustered as shown at https://www.backyardnature.net/n/11/111211ws.jpg.

If they'd been bees, I'd have thought that somehow already the little nest had produced a surplus population and now a new queen was leading part of the nest to someplace else where a new nest would be founded. However, I wasn't sure if wasps did that. I looked more closely at the nest.

The nest was swarming not with wasps but with ants. Fair sized ants poured out of the thatch, rushed across the nest's surface into the nest's teardrop-shaped entry hole, while others were already leaving the hole carrying white, paperlike flakes. The flakes were borne to the nest's bottom, where they were released into the air to flutter to the ground. Then the ants returned to the hole. At first I thought the flakes were wasp wings but up close I saw that they were the coverings of brood cells.

The wasp nest was being overrun by ants. Part of the wasps had escaped and now clustered on the Tree Cotton while the ants methodically tore apart the nest's interior chambers holding developing wasp pupae. Then ants began exiting the hole, not very tenderly dragging larvae beneath them, their sharp, ice-tong-like mandibles stuck into the pupae as shown at https://www.backyardnature.net/n/11/111211wt.jpg.

During this slaughter relative larger, red-headed soldier ants positioned themselves at the perimeter of action, their rear ends hunched beneath them as if they could sting, and their powerful mandibles open like incurved pincers ready to stab inwards, seen at https://www.backyardnature.net/n/11/111211wu.jpg.

In about half an hour the wasp swarm in the Tree Cotton departed. Until darkness fell the ants continued ripping open larval cells and carrying out white pupae, presumably to be butchered and distributed at their leisure.

The next morning the nest was empty, and quiet. During subsequent days from time to time wasps came and briefly surveyed the nest, but then flew away. Today the nest remains silent and abandoned.

By the way, down here the Maya still sometimes eat wasp larvae. There's a well illustrated recipe here.

*****

INSIDE A BASILISK'S MOUTH
A young Striped Basilisk turned up in the gift shop banging against a window trying to escape, so I was called to carry him outside. Basilisks are slender, fast-footed lizards with crests and very long hind toes. We've featured them often, as you can see at https://www.backyardnature.net/mexnat/basilisk.htm.

It was an immature one, with its crest just beginning to develop. Once he was secured in my hand he gamely gaped open his mouth, threatening to bite. He'd already bitten as I'd closed my fingers around him, but his teeth were tiny and he was too small to bite down hard, so it hadn't hurt at all. But while I had a basilisk with his mouth open in my hand, it occurred to me to look into his mouth to see if anything interesting was there. You can see exactly what I saw at https://www.backyardnature.net/n/11/111211bk.jpg.

What caught my attention were the two large holes in the mouth's back, where the jaws hinge. They're such conspicuous features that they must be important. I had to do a search on "lizard mouth anatomy" to figure it out: They're Eustachian tube openings. Eustachian tubes connect the middle ears to the nasopharynx (back of the throat) region. In humans they equalize air pressure on the two sides of the eardrums. However, human Eustachian tubes are narrow, inconspicuous structures. Why would a basilisk's be so relatively pronounced?

A little search-engine work brought up a paper on the "Evolution of sound localization in lizards," presented at a scientific meeting in New Orleans in 2007. It states that primitive middle ears -- which a basilisk would have -- are not enclosed in cavities, as are human ones, but rather open into the mouth cavity. The Eustachian tube openings we see in the basilisk mouth would represent that connection to the mouth cavity.

Animals with such arrangements thus have their two ears "acoustically coupled" through their mouth cavities. Sound waves travel from one eardrum through the mouth cavity to the back surface of the other eardrum, creating an "inherently directional pressure difference receiver," as the investigators term it, enabling the greatest directionality in hearing of all terrestrial vertebrates. There's more detailed and illustrated explanation freely accessible online at http://www.acoustics.org/press/154th/carr.html.

So, lizards like our basilisk enjoy a kind of "binocular vision" with their hearing, something that's much less developed in us mammals. Such direction finding ability would help a lizard locate bugs scurrying through loose debris on the ground.

While the basilisk was in my hand I photographed his head from the side, where you can see his facial scales and tiny teeth. Also, behind the jaw, there's an ear's circular interface with the outer world. It's at https://www.backyardnature.net/n/11/111211bl.jpg.

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KEYING OUT A KATYDID
You can see a katydid nymph -- a nymph being an immature stage of insect undergoing incomplete metamorphosis -- atop a Tree Cotton's developing boll at https://www.backyardnature.net/n/11/111211kt.jpg.

You know that it's immature because its wings are only partly developed. Also, it's a female, because of that curved blade-like thing at the end of her abdomen. That's an ovipositor, used for depositing eggs. I sent the picture to volunteer identifier Bea in Ontario who recognized it as a member of the Katydid Family just by looking, and further figured out that it was a member of the False Katydid Subfamily, the Phaneropterinae.

However, just in the False Katydid Subfamily there are nearly 2060 species in 85 genera worldwide, so I tried to narrow it down a little more. Fortunately, on the Internet I stumbled upon a nicely illustrated "Key to Families and Subfamilies of Katydids," at http://entnemdept.ufl.edu/walker/buzz/t000k1.htm.

Remembering that our critter was about 40cm long (1-¾ inches) and consulting features visible in our photo, with that key I could confirm Bea's diagnosis. Moreover, using the "Key to Genera of False Katydids" at http://entnemdept.ufl.edu/walker/buzz/s001k.htm I was further able to make a good guess that ours is an anglewing katydid, genus Microcentrum. I say "guess" because this key is for Florida, and we may have other genera here the key doesn't take into account. However, Microcentrum is a big genus so it's a good guess.

So, "female nymphal anglewing katydid"... Wikipedia says of members of the Phaneropterinae that "Their eggs are rarely deposited in the earth or twigs but are either glued fast in double rows to the outer surface of slender twigs or are inserted in the edges of leaves."

By the way, I think that the family name of "false katydid" just indicates that in some views an anglewing katydid isn't a katydid; it's an anglewing katydid...

More and more the Internet is becoming mind-bogglingly helpful as a resource for naturalists trying to understand what they're seeing. What an amazing moment in human evolutionary history we're all living in, and what a pleasure to be so vividly conscious of, and eager to participate in, that evolution!

*****

TROPICAL MISTLETOE FRUITING
Recently we saw that here we have mistletoe species very similar to those in the North. More eye-catching is our Tropical Mistletoe, genus PSITTACANTHUS, with its large, brightly red flowers, as seen ten feet up at https://www.backyardnature.net/n/11/111211mi.jpg.

You can see that this mistletoe's fruits are much larger, and black instead of the North's white, at https://www.backyardnature.net/n/11/111211mj.jpg.

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TSALAM
The above Psittacanthus mistletoe was parasitizing an acacia-like tree known in the Yucatán as Tsalam. It's LYSILOMA LATISILIQUE, a member of the Bean Family. Though its feathery leaves look like those of numerous other acacia-like tree species found here, at this time of year Tsalam is easy to recognize because of it's large, flat, legumes with enlarged edges along both sides and, most conspicuously, the odd manner by which the legumes' dark covering flakes off, making the pods look faded and abused, as shown at https://www.backyardnature.net/n/11/111211ts.jpg.

The Biblioteca Digital de la Medicina Tradicional Mexicana says that traditionally Tsalam's leaves have been roasted and pound into a powder to apply to sores and wounds. The tree also is used for asthma and coughs in general, but it's not said how.

On our own page written by my friend Louise in Mérida, about using natural dyes to color henequen fibers, Louise writes that Tzalam's "...bark or core wood gives a reddish brown tone. It is one of the dyes that will vary in intensity depending on the age of the tree or on the seasonal climatic conditions. The bark can be stored for a few days and still be effective. It is a natural mordant."

Louise's very interesting page with more info is at https://www.backyardnature.net/m/crafts/louise_v.htm.

Louise is a genuine fiber artist who produces not only beautiful bags made of local henequen fiber and dyed with natural dyes, but also exhibition pieces. You can see some of her work and read about henequen fiber at https://www.backyardnature.net/m/crafts/henequen.htm.

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PHELLINUS, THE WOOD-DECAYING FUNGUS
With its long dry seasons when entire months can pass without a single drop a rain, the Yucatán just doesn't support as many fungi as other more humid areas. Still, if you look around, you can find a few. For example, look at what I found encrusting the bottom of some firewood stacked too long outside at https://www.backyardnature.net/n/11/111211fu.jpg.

At first I thought it was another slime mold, but then I looked much closer and saw what's shown at https://www.backyardnature.net/n/11/111211fv.jpg.

Slime molds don't produce lower surfaces so regularly ornamented with pores as this. However, there's a whole huge group of fungi that do, known commonly as the polypores. However, polypore fruiting bodies normally have stems or attach to wood at their sides, forming a kind of shelf. This fungus was attached at its top, with its pores pointing downward, so that spores could fall from them.

Nonetheless, in a general and non-technical way, it is a polypore, albeit a remarkable one because of the way it encrusts woody lower surfaces. I think that it's the genus PHELLINUS, maybe Phellinus punctatus, but other similar Phellinus species exist, and some are as cosmopolitan in distribution as this one.

Phellinus fungi are wood decayers. Ours is obviously decaying dead wood, but Phellinus punctatus has been noted occasionally infecting live trees, causing plant pathologists to refer to it as "a true canker rot."

I've not seen it on any living plants here. However, the firewood pile from which I retrieved the stick was full of it.

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MAMEYS FLOWERING & FRUITING
Normally we think of a plant's flowering time preceding and separate from its fruiting time. Sometimes, however, flowering and fruiting overlap. That's the case nowadays with Mamey trees, as shown at https://www.backyardnature.net/n/11/111211mm.jpg.

Those unripe fruits are about three inches long (8cm). Eventually some of them may reach double that size, and when they do they'll offer themselves as one of the world's most delicious of tropical fruits.

You can see that one curious thing about the pea-sized flowers is that they are almost stemless and grow densely along the tree's thick branches. Other neat features about them are shown in the close-up at https://www.backyardnature.net/n/11/111211mn.jpg.

At that picture's top, left you see a recently pollinated blossom in which the corolla has been shed, falling off in one piece. The green fingerlike item poking out of the brown nestlike thing is the style, the ovary's "neck," atop which was the stigma on which pollen grains germinated. The brown nestlike thing is the calyx, which is unusual because it has ten sepals, or calyx lobes, instead of the expected five, and the lobes overlap like shingles on a roof -- they're densely "imbricated" in several series, the books say.

Lower down, a younger blossom retains its whitish, five-lobed corolla. The notable feature about it is that the corolla lobes alternate with slender "staminodia." Staminodia are thought of as sterile stamens, or features that arise where you'd expect stamens to arise.

In the field, if you see a flower with such overlapping sepals and staminodia alternating with the petals, you just have to think of the Mamey's family, the Sapodilla Family, or Sapotaceae. In the tropics worldwide that's a good family to know, because it so often produces scrumptious fruit. Beside mameys, there are chicozapote or sapodilla, canistel, and star-apple or caimito fruits.

The Mamey tree, POUTERIA SAPOTA, is a native tropical American tree, probably including southern Mexico, but it's not found in our local forests. It is, however, planted in the tropics worldwide for its wonderful fruit.

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THE WASP SLAUGHTER
You can imagine that, having watched the wasps so long building and caring for their nest, I had grown interested in their welfare. Seeing ants destroy their nest was poignant for me. However, experiences like that never leave me with just one feeling, or insight.

My first thought had been that this wasp slaughter was exactly the kind of thing that happens all the time in Nature, at all levels. And since humans are as much a product of, and profoundly enmeshed in Nature, as any fern or fly, both wasps and people have nothing watching over us making sure bad things don't happen. We're given a nudge at birth, then we're on our own.

The second thought was that once again we had one of those Yin-Yang situations, where everything has both "good" and "bad" sides and at the heart of every "good" there's always a seed of "bad," and vice versa. For, maybe the overall local wasp community actually benefits from such occasional attacks "thinning them out." Otherwise, ever expanding wasp numbers might deplete the wasps' local prey, until famine and/or disease did much more damage on the wasps than any ant raid. And, it's true that several other wasp nests likewise hung in the hut's thatch, more than normal for a typical Maya hut.

The third thought was that of all Earthly creations, there's only one instance in which a living thing can escape the need for Nature's harsh methods of keeping things in balance. That single instance lies with us humans, who can overcome impulses arising from genetic programming that may have served our distant ancestors on the African savannah well, but which now are inappropriate, even deadly. For example, wasps can only keep breeding unthinkingly until they're so overpopulated that something has to reduce their numbers for them. But we humans can consciously control our numbers, if we think, feel and act.

The fourth thought arising from the ant attack was that at this moment in the evolution of human development, surely the most dignified goal a person can have is this: To identify, reflect on, and take action with regard to his or her own vestigial, self- destructive, genetically programmed impulses.

How beautiful that Nature teaches in such easy-to-comprehend, generous ways, if we only pause, look, wonder, and think.

*****

Best wishes to all Newsletter readers,

Jim