November 15, 2015
BIG WOLF SPIDER
Reaching for a sandal, something nervously bobbed to one side as my hand approached. It was the big wolf spider shown at http://www.backyardnature.net/n/15/151115sp.jpg.
I'd been looking forward to this event, for back in 2009 upon my arrival here at Hacienda Chichen I'd photographed this same species with a captured House Gecko. The story, with pictures taken in dim light and not doing the handsome spider justice, can be reviewed in a Newsletter issued, like this one, on November 15th -- at the bottom of the page at http://www.backyardnature.net/yucatan/wolfspid.htm.
Now, at last, right here on my sandal was the very same species and this time I had plenty of light. Just look at the dignified creature's portrait at http://www.backyardnature.net/n/15/151115sq.jpg.
The world's many wolf spider species generally hunt in the dim light of dusk, and by moonlight. In general they display two hunting strategies: either they sit quietly waiting for prey to pass by, or else they go out hunting, like tiny wolves. Though they have good eyes, they react mainly to vibrations caused by potential prey beating their wings, or walking on the ground. They eat many kinds of invertebrates, such houseflies, crickets, cockroaches, occasionally grasshoppers, and we've seen that our big ones can eat vertebrates as well, in the form of house geckos.
Identifying our present one with its red-rimmed goggles turned out to be a challenge. I'm pretty sure our sandal-sitting individual belongs to the traditional wolf-spider genus Lycosa, but of that genus about 235 species currently are recognized worldwide. The Wikipedia species list for Lycosa mentions 14 species found in Mexico. One of those species is LYCOSA MAYA, the species name suggesting its presence here in the Yucatan. Unfortunately, on the Internet I find no photographs or descriptions of that species and can't confirm that that's what we have. But that's the closest I can come to offering a name.
Lately many authors have shifted Lycosa species to the genus Hogna, but there seems to be resistance to this change, maybe because Lycosa -- the Lycos being classical Greek for "wolf" -- is such a well established and appropriate name.
THE WOLF SPIDERS' LIGHT-REFLECTING EYES
Having been reminded of the world of wolf spiders, one night this week I recalled when I lived in Belize, taking visitors on night-walks around the forested hill where I worked. The highlight usually was when I'd invite each person to hold a flashlight with its end against his or her forehead, and with the beam of light projecting in front, gaze onto the forest floor around them. The floor would sparkle with tiny lights, and I'd explain that these were wolf spider eyes reflecting light back at them. To prove it, we'd approach a gleaming object close enough to see the spider with its blazing eyes.
This week I wondered if my camera could capture such a scene, for I knew spidery eye-glistens surrounded the little hut like a thickly populated countryside's collection of little homes with backyard lights left on. I experimented with placing the camera on a chair, with its lens aperture at its widest and with a shutter speed of about a second, and with a two second time delay, clicking the shutter, and pointing a flashlight into the woods, from behind the camera, and I got fair results. However, simply by placing the camera on automatic and opening up the flash I got better results. You can see pinpricks of bright spider-eye light in a flashed picture shown at http://www.backyardnature.net/n/15/151115sr.jpg.
The several sparklings visible on the ground, rocks, twigs and leaves represent only a fraction of the spider population actually present, for if you and your flashlight move just a little to one side, the gleamings disappear, while others appear. A spider needs to be turned a certain way for its eyes to reflect light. However, wolf spiders bear eight eyes, so there's a fair chance that one or more will be staring in your direction.
In our "Wolf Spider Nabs Gecko" piece, the first picture provides a side view with one of the spider's back-side eyes silvery with reflected light. That's as it should be, because a wolf spider's four "posterior eyes" have especially well-developed "tapeta." The tapetum -- singular for tapeta -- consists of a disc-like layer of light-reflecting crystals behind the eye's light-sensitive retina. The tapetum increases visual sensitivity because light entering the retina is immediately reflected back through them by the tapetum, thus intensifying the image at the retina. Therefore, wolf spider eye-sparkles consist of light bouncing off the eyes' tapeta.
This week I approached several glistens on the forest floor, but none was made by the same species as our sandal sitter. They were much smaller individuals of different species, so small that it was hard to imagine how such intense light could reflect from their eyes. My impression is that our big ones like the sandal sitter are most common around buildings.
About four years ago I planted a pad of Nopal Cactus -- a spineless, edible species much cherished by Mexican country folk who eat its pads and fruits -- in front of the hut. Now the cactus consists of many pads and stands higher than my head. One morning this week I noticed some bugs on it apparently making themselves at home, which included feeding on the cactus and procreating on it, as shown at http://www.backyardnature.net/n/15/151115bg.jpg.
A close-up showing a prettily stripe-faced one with his slender, strawlike proboscis inserted into a pad is shown at http://www.backyardnature.net/n/15/151115bh.jpg.
In calling this species a bug I'm using the term "bug" advisedly, because these critters are members of the insect order Hemiptera, known as "true bugs." Technically, ladybird beetles aren't bugs, because they're beetles. But these bugs on my Nopal, with their distinctive sucking mouthparts and four wings, with the front wings thickened at their bases, are classic bugs, technically correct bugs, in fact "true bugs." As a kid on the Kentucky farm, the best-known true bugs were "stinkbugs," whose shapes were very similar to these, and who stank defensively if poked at too roughly.
But these cactus-living bugs outside my hut door aren't stinkers. Still, the world of True Bugs is so enormous and diverse that just about any kind of behavior can be expected of one or another of its species, not just stinkiness.
I was especially interested in these bugs' identity because during my recent stay in Río Lagartos the tops of fenceposts throughout the surrounding country often were affixed with yellow, harmonica-size items the shapes of prisms, their ends open and their interior walls coated with flypaper-stickiness, and pheromones. The pheromones attracted a certain kind of insect whose hungry larvae threaten to destroy many of Mexico's Nopal Cactus plantations. We don't have big Nopal plantations in the Yucatan, but in the dry uplands of central and northern Mexico they do. The pheromone traps were monitored regularly to watch for the destructive bug's appearance here. Therefore, could these bugs on the cactus outside my hut possibly be one of them? The pictures were sent off to volunteer identifier Bea in Ontario, who with her usual expertise quickly replied that they were LEPTOGLOSSUS SUBAURATUS.
It turns out that Leptoglossus is a diverse and complex genus, with 61 species recognized in the Americas. Since true bugs sometimes are of importance to agriculture, they're better studied than some other orders, and it was possible to download Harry Brailovsky's 2014 work in the journal Zootaxa, the title of which begins -- in case you want to Google it -- "Illustrated key for identification of the species included in the genus Leptoglossus... "
The Internet is peppered with lists showing that Leptoglossus subauratus collected has been collected here and there in places from southern Mexico to Costa Rica, and a few notes detail such matters as the species' tibia length and the color of its pronotal disk, but there's hardly any information out there describing the bug's behavior, except for one note that a collection was made on a cactus. Apparently Leptoglossus subauratus isn't the bug decimating some of Mexico's cactus plantations, else surely it would be mentioned somewhere.
So maybe our entry here will help a graduate student someday by letting them know that here in the Yucatan in mid November, Leptoglossus subauratus can be found feeding and mating on Nopal Cactus, Opuntia ficus-indica.
In the summer of 2003 I was living as a hermit in the piney woods near Natchez, Mississippi, next to a tangle of Moonflower vines cascading over a barn door. Several plants with large, white blossoms that open at night bear the Moonflower name, but the one I'm talking about is a member of the Morning Glory Family, IPOMOEA ALBA.
In that's year's August 24 Newsletter I wrote that "The Moonflower knows how to build up suspense as the moment of blooming approaches. For several days you are impressed by the development of the large, green flower-bud."
Then I passed on my notes from a highly anticipated Moonflower blossoming:
"By Tuesday evening my bud had grown to exactly 6 inches long (15 cm). An hour before sunset the bud's spiraling pleats began bulging, revealing streaks of the flower's pure whiteness within. I placed my rocking chair next to the 17-ft-high vine (5 m) and waited. At first the blossom's opening proceeded too slowly to see, but, finally, exactly as the sun slipped below the horizon, and the flower was held closed only by the tips of its petals, suddenly the tips came loose all at once and the flower partially opened instantly, releasing a puff of perfume that almost staggered me."
"At dawn the next morning the flower's corolla closed like a crumpled paper bag. All day it remained shut beneath the bright sun, then an hour or two before dusk it fell off, leaving the ovary to develop into a fruit. That evening, Wednesday, two more blossoms opened, and I've had one to four blossoms each night since."
I'm not the only one who savors Moonflower openings. Ana María, a Newsletter reader in the Yucatán -- and the first to invite me here for what became a long-term presence -- wrote to me about her own experiences with Moonflower watching.
"On the night she expected her first bloom," I reported in the Newsletter, "she invited friends to experience the opening. They had a fine supper, then went out to see the opening -- and the entire flower bud that was supposed to open had been eaten by caterpillars! However, in two nights there was another bud to watch, and once again the friends came, there was a delicious meal topped off with an exquisite tarta de manzanas, or apple tart, and this time the blossoming surpassed expectations."
This week these memories flashed through my mind the moment a rampant tangle of wild Moonflower vine turned up along the road between the Hacienda and neighboring Xcalacoop. It was just a little after dawn on a foggy morning, with the pale sky only hinting that the sun might be above the horizon, yet already the vines' big blossoms were puckinger in their corollas, as shown at http://www.backyardnature.net/n/15/151115mn.jpg.
In that picture, notice that some leaves are heart-shaped with no lobes or teeth, while others are deeply lobed. Leaves of wild plants are very variable, being 0-5 lobed. A picture of a gigantic flower bud that surely would open the following night, with my hand as scale, is shown at http://www.backyardnature.net/n/15/151115mo.jpg.
Because the Morning Glory Family, the Convolvulaceae, is so big, and so many species occur in Mexico, often it's hard to figure out which species you have. However, Moonflower vines display such distinctive features that they're easy to recognize. Besides the huge blossoms that open at night and close in early mornings, and stamens hat extend beyond the corolla's center hole -- the stamens of most species hide within the corolla tube -- one good field mark is that the calyx's outer sepals bear on their backs long, slender, fleshy projections such as those shown on calyxes from which the flowers have fallen at http://www.backyardnature.net/n/15/151115mq.jpg.
Another is that the stems below where the flower clusters attach normally bear low, blunt teeth such as those shown at http://www.backyardnature.net/n/15/151115mp.jpg.
Though Moonflowers grow wild throughout Mexico and Latin America, as well as the US Southeast, it's hard to say where they originated. For their beauty they have been planted all over the world and in warmer lands have often escaped, giving the appearance of being a native plant. Linnaeus first described the species in 1753, using a plant from India.
MADAGASCAR DRAGON TREE
At a hotel across the road from the Hacienda, at Villas Arqueológicas, I've never been quite sure about the multi-trunked, 15-ft-high (4.5m) tree shown at http://www.backyardnature.net/n/15/151115dc.jpg.
A look at a single tuft of blades at a stem tip is shown at http://www.backyardnature.net/n/15/151115dd.jpg.
It's not a palm because its leaves are sword-shaped, not fan- or feather-like. Its leaves gathered in tufts at the end of long, naked branches suggest a yucca, but I've been watching this plant and others like it for years and have never seen white flames of yucca flowers igniting from the stems. The leaves don't have wiry filaments curling from their margins like some yuccas, and they seem softer than normal yucca blades. Also, the stem is unlike any yucca stem I recall. A close-up showing broad, shallowly U-shaped petiole scars is at http://www.backyardnature.net/n/15/151115de.jpg.
Finally, a Google image-search on yucca species turns up nothing looking like this.
Therefore, I began checking closely related genera -- genera in the same family as yuccas -- and quickly was drawn to the genera Dracaena and Cordyline. We've looked at a pretty, tree-like Cordyline at the Hacienda, the Ti Plant, shown at http://www.backyardnature.net/yucatan/ti-plant.htm.
That species has much broader leaves that aren't tufted, so it's not that.
After doing image searches on tree-like species of both Dracaena and Cordyline, finally something turned up looking exactly like our plant, though most photos showed smallish plants in pots up North, not leggy, 15ft-tall, clumping ones like ours. Judging from pictures on the internet, it's unusual to see such large members of the species as this one.
It's DRACAENA MARGINATA, sometimes known as the Madagascar Dragon Tree. Madagascar, because originally it's from that big island off the African coast in the Indian Ocean, and Dragon Tree because a more famous species in the same genus exudes red sap when injured, and some dreamy botanist someplace once thought to associate the red sap with blood that sprang from the dragon slew by Hercules. Sap of our Dracaena marginata, however, isn't red, so the Dragon part of the name is a bit silly, but the species seems to be stuck with it.
Madagascar Dragon Trees are favorites for malls up north. Maroon color, multicolor and rainbow varieties have been developed. In general, Dracaena species need heat, and many species are very drought tolerant. They produce flowers but this species' are small, and I guess I've just missed them.
JARVIS'S SOLAR POWER SYSTEM
My friend Jarvis in North Carolina, a freshly retired college professor, had a house built for himself, and since Jarvis is a thoughtful, responsible individual he wanted it equipped with solar power. You can see what he ended up with at http://www.backyardnature.net/n/15/151115jv.jpg.
Now that Jarvis has lived in his house for a year or so I asked him how his solar system had worked out, for sometimes when we hear about solar power, it's hard to know what's solar-power industry hype, what's coal and nuclear industry negative propaganda, and what's the truth. And Jarvis would tell the truth. He replied:
"I am very pleased with my solar power system. It generated more power than I used in every month from April through October. Also, in March I almost broke even, so that my cost for electricity consumed in March was $1.38."
"I found that in the summer I was consuming an average of about 5 kWh per day. In the summer I use the air conditioning some but not much. In the winter I was consuming an average of about 35 kWh per day. The heat pump uses a lot of power even though I used the wood-burning stove for heat on some very cold days."
"I have to pay a flat fee of $12.80 per month for being connected to the grid even if I don't use any electricity. But one advantage of being connected to the grid is that I can get credit for excess power I put into it. I am estimating that I will be able to use my credits from November through January so that I don't have to pay anything for power consumed in those months (but I still have to pay the flat fee of $12.80 per month). I estimate that in February I will have to pay about $22 for power consumed. So, my estimate for the total I will have to pay for power consumed during 2016 is $26. ... I haven't completely eliminated my dependence on fossil fuels for electricity generation but I have gotten very close."
"There is something else that people should be aware of. ... If you use solar power you should have an energy-efficient home if you really want to get the benefits. Otherwise you could still have big electric bills."
FEATURED ESSAYS FROM THE PAST:
"Dewdrop," from the February 6, 2012 Newsletter, at http://www.backyardnature.net/n/p/120206z.htm.
"Deer in The Scrub," from the September 1, 2008 Newsletter, at http://www.backyardnature.net/n/p/080901.htm
Best wishes to all Newsletter readers,
All previous Newsletters are archived at http://www.backyardnature.net/n/.