JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from the valley of the Dry Frio River on the
southern slope of the Edwards Plateau, northern
Uvalde County, southwestern Texas, USA

December 22, 2013

WINDOW BUGS
For the last couple of weeks bugs have been congregating on Juniper House's big windows, sometimes two or three on a single pane. I'm using the term "bug" in its particular sense, meaning that they're members of the True Bug Order, the Hemiptera.

True bugs bear piercing mouthparts -- strawlike proboscises that they insert into plants or animals for the purpose of sucking out juices. Another field mark for true bugs is that their forewings display both membranous and hardened parts. Beetles aren't true bugs because their forewings are hard throughout. Butterflies aren't true bugs because their forewings have no solid parts. You can see the true bug that visits our windows at http://www.backyardnature.net/n/13/131222lf.jpg.

The long, slender, segmented proboscis curved downward from between its antenna bases can be seen at http://www.backyardnature.net/n/13/131222lg.jpg.

In that picture you might also notice the tiny, black parasite atop the bug's head, just behind the eye. Also, as I was holding the bug for the picture I was reminded of another name often given these bugs: stinkbugs. The bug emitted onto my fingers a very powerful and unpleasant smell that was hard to wash off.

Anyway, the piercing mouthparts often get true bugs into trouble with humans, and vice versa. In the Yucatan a true bug known as the Chinche Hocicana could give you deadly Chagas Disease if it pierced you with its proboscis. In our part of the world true bug proboscises cause more problems being inserted into fruits and vegetative parts of crop plants. So, is our window visitor one of those who inserts its proboscis into places we don't want it to?

Volunteer identifier Bea in Ontario helps us answer that by providing our bug's identity. It's the Western Leaf-footed Bug, LEPTOGLOSSUS CLYPEALIS, which occurs spottily in North America, from Ontario to California, though mostly in the southwestern states, and into Mexico. Several leaf-footed bug species are very similar to this one. The best field mark distinguishing our species may be the especially conspicuous "clypeus," which is the yellow-orange, needle-like projection pointing forward on the head, arising between the antennae.

Western Leaf-footed Bugs have been known to cause damage in California's pistachio and almond orchards, where they damages the seeds. However, normally the bug's populations are kept low by a parasitic wasp of the genus Gryon, which is an egg parasite of leaf-footed bugs. The wasp's larvae develop inside the bug's eggs, killing the bug embryo. Western Leaf-footed Bugs also spread diseases by traveling from diseased trees to healthy ones.

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MYSTERY EXUVIA
Down on hands and knees looking for mosses producing sporangia to identify (none found) I came upon one of the weirdest things I've seen in a long time, which you can see at http://www.backyardnature.net/n/13/131222ex.jpg.

Sticking from the soil, it was about 3/8ths inch high (1cm). It sort of looked like a cicada skin, but they display mouthparts and legs, while this bore neither. On the head, spines are pointed forward, and just below the spines the skin is ripped open. The object apparently got there by its own movement, despite there being no legs. Reviewing the metamorphosis formula to see when such a thing might result -- egg --> larva --> pupa --> adult -- none of this made sense.

I sent the picture to Bean in Ontario, telling her I suspected it was a pupa exuvia, the word exuvia referring to remains of an exoskeleton and related structures left after insects, crustaceans, arachnids and the like have molted. Bea Googled the keywords "pupa exuvia" and to our astonishment, at BugGuide.Net, an identified picture perfectly matching ours turned up.

In BugGuide's terms, what we have is an "Asilid Pupal Case," which translates into "the discarded exoskeleton of the pupa of a robber fly." Robber flies belong to the Robber Fly Family, the Asilidae. You can see an adult robber fly found here last May at http://www.backyardnature.net/n/a/rob-fly.htm.

So, how did the exuvia of a robber fly pupa end up poking from the ground? The mystery is solved upon learning that pupae in the Robber Fly Family are "exarate," which means that the pupa's legs and other appendages are free and extended. Despite our seeing no indications of legs in our photo or the photos of others on the Internet, anatomists tell us that they're there, so we must be overlooking them. Knowing this we can imagine this discovery's story:

After spending one to three years underground, at first probably eating decaying plant material but after growing larger and molting tending to eat invertebrate animals in the soil. The last larva stage forms a pupa presumably oriented with the front end with its spikes pointed upward near the soil's surface, maybe the spikes dissuading creatures like mice from poking their noses onto it. When the grub is ready to metamorphose into an adult robber fly, with its hard-to-see legs it tunnels to the soil's surface, and a little beyond, so that the adult can emerge from a split at the top of the pupa's exuvia and escape into free air.

Wikipedia has an unusually detailed account of the life history of robber flies at http://en.wikipedia.org/wiki/Asilidae.

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TADPOLE SNAIL
Maybe the most common aquatic snail in the little Dry Frio River is one with a ¼-inch-long (7mm) shell, shown at http://www.backyardnature.net/n/13/131222sn.jpg.

Actually, in most parts of the Dry Frio I can't find any snails at all, probably because the streambed and aquatic vegetation are so heavily coated with calcium-rich marl that a snail can't get a decent foothold, or maybe because too much marl would have to be ingested to get the organic detritus or algae it wants to feed on. However, in the river's stagnant pools and arms the marl isn't as thick, and there snails turn up, especially the one shown above. With the broadly oval shape and spottiness of its shell and broad head, it's easy to distinguish from other snail species. You can see the shell from below, displaying the teardrop-shaped, unusually long and open "aperture" through which the snail's body extends at http://www.backyardnature.net/n/13/131222so.jpg.

A couple of these snails were given homes in fishbowls in Juniper House, and you can see what one looks like through glass as it climbs the wall at http://www.backyardnature.net/n/13/131222sm.jpg.

Often to determine a snail's identity you need to dissect it, but I feel fairly confident about who this one is just based on the general features noted above, and the fact that so many identified snails on the Internet look like it. It's PHYSELLA ACUTA, which goes by many names, including Tadpole Snail, Bladder Snail, Left-handed Pond Snail, Pewter Physa and Protean Physa. Maybe the Tadpole name arises from the fact that some tadpoles bear spots like this snail's shell. The reason the snail has so many common names is that it occurs in freshwater practically worldwide and in many places is the most commonly occurring species. It's so cosmopolitan that it's hard to say where it's native to, or maybe it's native to everyplace.

Another reason for confidence in the name is that snail expert Richard Fullington has surmised that the Tadpole Snail is "... probably the most common freshwater snail in the southwest US" and "probably occurs in every Texas county."

Finally, snail species come in right-hand and left-hand models. Tadpole Snails are listed as "sinistral," which means that if the shell is held with the aperture facing the observer and with the spire pointing upward, the aperture falls on the left-hand side. That checks out with our snail.

Tadpole Snails are so common because they are highly adaptable and tough. The can live in freshwater rivers, streams, lakes, ponds, swamps, manmade reservoirs, warm water discharges of power plants, and ditches. They survive well under temporary temperature extremes and high pollution levels. In fact, they've been recorded as serious pests in greenhouses and filtering vegetation at sewage treatment plants. Also, they mature rapidly and have a high reproductive rate. They've been called "the fruit fly of malacology," malacology being the study of mollusks.

They eat dead plant and animal matter, or detritus, their preferred grazing sites being submerged plant surfaces.

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EVERGREEN SUMAC FRUITING
The other day I peeped over a limestone ledge beside the Dry Frio and saw the pretty picture at http://www.backyardnature.net/n/13/131222su.jpg.

I'd been looking for this because I knew it'd be a nice sight, and just a while back we saw a flowering one, so I knew they were in the area. It's the Evergreen Sumac. You can see what it looked like in October at http://www.backyardnature.net/n/w/rhus-vir.htm.

Another reason to look for an Evergreen Sumac with fruits is that the literature reports that the fruits can be soaked in water to produce a tart tea. Back East I've often made tea with the Staghorn Sumac's red fruits, which are covered with glandular hairs. When those fruits are placed in hot water the glands burst releasing acid into the water, which tastes good, a bit like lemonade.

However, this tree was inaccessibly clinging to a cliff face so I'll have to wait to try that.

There's the matter of how to pronounce "sumac." I was taught to call it SHU-mak, and the online Merriam-Webster Dictionary gives that as the first pronunciation, with SU-mak the second. Other dictionaries usually say the same. When I was a kid "SU-mak" was regarded as absolutely wrong, pronounced that way only by people who didn't know how to say it, and were pronouncing it as its spelling suggests, which was as "wrong" as pronouncing "knight" the way it looks. Nowadays so few people have connections with grandparents who grew up using its traditional pronunciation that now mostly I hear SU-mak. Probably eventually the original pronunciation will disappear, as has nearly happened with the word "often," for nowadays nearly everyone pronounces the t, just because it's spelled that way.

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SILVERPUFF
I keep thinking I've seen my last new-for-me wildflower of the year, but new ones keep coming along. This week in grass on deep soil at the shady base of a low limestone ridge running along the Dry Frio River the vaguely dandelion-like, one-flowered herb turned up shown at http://www.backyardnature.net/n/13/131222ch.jpg.

The plant had already flowered, so the nodding, head shown on its leafless stem, or peduncle, consists of a collection of white-parachuted fruits that will be dispersed with the wind, like those of the dandelion. Of course, seeing the head structured so like an almost-mature dandelion head, we know that the plant, like the dandelion, is a member of the Composite, Daisy or Sunflower Family, the Asteraceae.

Up close you can better make out the white hairs forming the parachutes, especially because one fruit has worked its way out of the head, deployed its parachute, and is about ready to fly away. This is shown at http://www.backyardnature.net/n/13/131222ci.jpg.

That picture also provides a fine view of the greenish, overlapping, sharp-pointed scales known as phyllaries, which constitute the involucre inside which the florets and fruits develop. Note that the phyllaries and peduncle are both mantled with white, cobwebby hairs. On the fruit that's ready to fly away we can see that its parachute hairs actually are a little tawny colored, and that instead of arising directing from the long, narrow, three-ribbed, cypsela-type fruit, they radiate from the tip of a slender neck atop the cypsela, as seen at http://www.backyardnature.net/n/13/131222cj.jpg.

The plant's leaves all arise from the ground forming a basal rosette. They're also covered with white, cobwebby hairs, though their tops are much less densely hairy than their bottoms, which are surprisingly white and fuzzy-feeling, as shown at http://www.backyardnature.net/n/13/131222ck.jpg.

Despite retaining no flowers -- which the Flora of North America tells us are cream colored, turning crimson -- this wildflower is unusual enough with its single, nodding head and basal leaves mantled with cobwebby hairs that it was easily identified as what often is called the Silverpuff, CHAPTALIA TEXANA. Silverpuffs are distributed mostly in arid northern Mexico, but extend into the US in south-central New Mexico and southern Texas. The Flora of North America describes its habitat as "Slopes in thin, rocky (limestone) soils, usually in woods with abundant oaks; 200–1500 m," and that's exactly where it occurs here.

The genus Chaptalia is limited to the Americas, with its sixty or so species being mostly tropical and subtropical. Three species occur in the US. In Texas some botanists recognize the species Chaptalia carduacea, but most experts regard this as no more than a regional variation of C. texana, and the Flora of North America doesn't even deign to mention it. If someday C. carduacea is more generally recognized, then our plant would fit best under that name.

In Duke's Handbook of Medicinal Plants of Latin America, the species Chaptalia nutans, of which our C. texana sometimes has been regarded as a variety, has been used traditionally for "cleansing the blood and digestive system as part of an aphrodisiac," plus so many other uses are documented that you wonder if any are valid.

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PRAIRIE BLUETS IN WINTER
Back in June we looked at the common and pretty little wildflower called Prairie Bluets, Stenaria nigricans, shown at http://www.backyardnature.net/n/h/bluets.htm.

Now the Prairie Bluets' flowers have long fallen away and the herbage that's so green and lush in the picture has acquired a purplish cast from the frost, and tiny capsular fruits are split open distributing their seeds whenever the plant is hit or shaken by the wind. You can see a plant in its winter condition at http://www.backyardnature.net/n/13/131222bl.jpg.

A close-up of some capsules -- the one at top, right not yet open but two others already open and releasing their seeds -- appears at http://www.backyardnature.net/n/13/131222bk.jpg.

That picture shows that the capsules split along sutures crossing the fruits' tops. Also, the unopened capsule displays short, slender sepals arising from its midsection. From this we determine that the fruit is "inferior," the term used for flowers in which stamens and sepals do not arise below the ovary, but rather above the ovary's base. The capsule with its elevated sepals is what became of the inferior ovary. This makes sense because bluets are members of the Coffee or Gardenia Family, the Rubiaceae, which in a world where most flowers are "superior" produces "inferior" ones.

Elsewhere in North America bluet species are found looking very much like this, except they are annual members of the genus Houstonia, not perennial members of the genus Stenaria, like ours. You can see our Prairie Bluets' springy-looking rosettes of next season's leaves arising from a woody base, with this season's purplish, dying-back stems rising above them, and even traces of last year's decaying stems on the ground, at http://www.backyardnature.net/n/13/131222bj.jpg.

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NITELLA
In some places the little Dry Frio River disappears completely into gravel banks only to reappear a little downstream issuing from a similar gravel bank. In some places, however, there's enough water to form pools in which aquatic vegetation survives year round. In such spots we've identified several aquatic flowering plants, such as pondweed and water milfoil, and several algae. This week something new turned up, and at first I wasn't sure whether it was a flowering plant or an alga. You can see its pie-sized, fan-shaped colony heavily coated with calcium-rich marl mud and consisting of bean-size, spherical clusters arrayed atop one another on numerous long, pliable stems, like shish-kebabed Brussels sprouts, and directed downstream by the flow, at http://www.backyardnature.net/n/13/131222nt.jpg.

Even after parts had been shaken and washed to remove the marl, the pieces were so matted and disfigured that it was hard to make much of the organism's anatomy. However, after stem segments had lived in a fishbowl for a couple of weeks, new sprouts arose bearing clean, well-formed appendages. You can see them amidst bubbles of freshly photosynthesized oxygen, with the camera shooting downward over the water's surface inside the fishbowl, at http://www.backyardnature.net/n/13/131222nu.jpg.

Seeing no traces of vessels or stem nodes, now it's apparent that instead of a flowering plant we have an alga, and remember that algae are not regarded as plants, animals or fungi. Though they photosynthesize like plants, they lack many cell organelles and cell types found in plants.

Last August, also in the Dry Frio, we found another alga with slender appendages arranged is frilly whorls along the stem. That was Chara, which you can review at http://www.backyardnature.net/n/x/chara.htm.

This plant was different from Chara in that its parts were smaller, much softer and smoother, and not covered with brittle calcium crust.

However, in the Chara Family of algae, there are different genera, and this week's find was one of them. It was a member of the genus NITELLA, which most folks just call Nitella, though sometimes they're called Stoneworts. Several species of Nitella are known and they are widely distributed, but I can't say which species this is.

Actually, Nitella and Chara have no real stems, but rather hollow, stem-like structures with forked branches along their lengths. Plant stems have water-conducting vessels, nodes and other details not found in algae such as Nitella and Chara.

In stream ecology, both Chara and Nitella often form "underwater prairies" in which many micro and macro invertebrates graze and find shelter. These invertebrates in turn are preyed on by fish, amphibians, reptiles, ducks, etc.

In evolutionary biology Chara and Nitella are interesting because current evidence suggests that about 500 million years ago the first plants probably evolved from shallow freshwater algae much like Chara and Nitella.

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FOSSIL WORMHOLES
Along the Dry Frio not far from here there's the spot shown at http://www.backyardnature.net/n/13/131222rv.jpg.

That's mudstone, and standing there seeing what looks like so many odd-sized bags of flour packed together, it's easy to imagine that the mud from which it was formed was deposited fast -- so fast that it didn't settle in neat, thin layers but rather large lumps that rolled around in rushing water collecting with other lumps in eddies, and eventually being buried beneath more mud. And all this happening ±110 million years ago, during the Early Cretaceous Period, when dinosaurs roamed the area. The approximate date of the mud's deposition is known because these rock strata are members of the Glen Rose Formation, whose age has been determined, at the beginning of Cretaceous Era. You might enjoy looking at our page on dinosaur tracks in our area, including a picture of tracks found near Glen Rose, Texas, at http://www.friocanyonnature.com/dinosaur.htm.

In the lumpy mudstone shown above I've found no fossils, but that's to be expected if the mud was deposited so fast and maybe violently -- as during a hurricane or a monumental flood -- that no creatures could have lived there.

However, atop this mudstone formation there's a shallow layer of limestone composed of very fine, clay-like particles and microscopic animal shells that was deposited much more slowly in a more tranquil environment, maybe in a mudflat or shallow sea. A picture taken looking down on that unit is shown at http://www.backyardnature.net/n/13/131222rw.jpg.

The holes were made by worms burrowing through the mud ±110 million years ago. Probably these aren't the original holes. It's more likely that the tunnels were filled with something that within the last million years or so eroded away faster than the surrounding limestone. The holes are not mere pits; in many places you can hook your finger into one hole and out the other.

This stratum of abundant worm burrows is fairly thin, but you can follow it for a good distance in outcrops along the Dry Frio's low cliffs.

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WINTER SOLSTICE
Yesterday, December 21, was 2013's Winter Solstice. The ruins at Chichén Itzá, Stonehenge, Egypt's Temple of Karnak, New Zealand's Aotearoa Stonehenge and many others are oriented with respect to the Sun during solstices, so we know how profoundly important solstices were to our ancestors.

But, now also we know you don't have to pray to the gods to ensure that days grow longer. No rituals or human sacrifices are needed. It's all a matter of the Earth's tilt on its axis as it orbits the Sun once a year. The whole thing is as inevitable and commonplace as an object in sunlight casting its shadow where it's supposed to.

This week news came from an epilepsy study that accidentally revealed something new about the human brain, an insight I've been thinking about during the Solstice. The research found that a certain part of the brain is responsible for a person's perseverance. Stimulate that brain region and you feel like fighting on no matter the challenge; no stimulation, and maybe you want to give up. The study is at http://www.wired.com/wiredscience/2013/12/the-will-to-persevere/.

In fact, several discoveries have been made like this. We've all seen photos of brains with specific points lighting up when the brain owner felt love, envy, happiness, or was thinking of spiritual matters. And people's brains certainly can be manipulated with chemicals to change our feelings, whether its beta-blockers mellowing us out, marijuana spacing us out, or caffeine making us alert. Suicide and aggression are associated with changes in serotonin; psychosis and addiction with dopamine; anxiety and mood disorders with norepinephrine. Susumu Tonegawa at the RIKEN-MIT Center for Neural Circuit Genetics even manipulated individual neurons in mice brains thereby inserting "false memories."

So, what does the Winter Solstice have to do with these studies suggesting that our thoughts and feelings may not issue from our unique souls acting freely, but rather as a consequence of hormone levels and how our neurons interact?

The connection is that with both the Solstice and the domain from which human desires, fears and spirituality arise, what at first seems magical now turns out to be commonplace, even mechanical. But, in both cases, that's OK.

For, when we visualize the Sun and the Earth's orbit and rotation in vast empty space, it's clear that even if the Solstice's special effects merely result from basic physics, still it's all majestically beautiful, profoundly mysterious if only because it exists, and worthy of reverential reflection.

It's the same with us humans discovering that our thinking, feeling and behaving are at least partly, maybe mostly, or even entirely governed by our genes and other prosaic and manipulable features of our bodily electrochemistry.

Just the fact that we are here, and especially that right now we are philosophizing about our own condition, and finding beauty and mysteries worthy of reverential reflection... is a worthy spiritual insight to meditate on during this Winter Solstice.

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FEATURED ESSAYS FROM THE PAST:

"Thoughts for The Winter Solstice" from the December 21, 2003 Newsletter, at http://www.backyardnature.net/n/p/031221.htm

"The Winter Solstice as Seen from Mexico" from the December 19, 2004 Newsletter, at http://www.backyardnature.net/n/p/041219.htm

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.friocanyonnature.com/n/.