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

March 10, 2013

ROADRUNNER
White-tailed and Axis Deer, Desert Cottontails, Eurasian Collard Doves and other critters roam the little gravel road in front of the cabin as if humans here weren't much of a bother, and usually we're not. If someone in a pickup-truck rattles down the road, wildlife just steps into the tall grass and junipers and let the vehicle pass, then return to the sun and wind to continue their perambulations. You can see one such traveler running briskly down the road at http://www.backyardnature.net/n/13/130310rr.jpg.

That's the Greater Roadrunner, GEOCOCCYX CALIFORIANUS, the "Greater" in the name meant to distinguish it from the slightly smaller Lesser Roadrunner we've met in Mexico.

Field guides show that the Greater Roadrunner is distinguishable from the Lesser by its more heavily striped throat and chest, and bigger bill. However, the throat and chest of the bird in the above picture don't look much different than the throats and chests of Mexico's Lesser Roadrunners, and neither do I notice much difference in the bills. You can see what you think by comparing the above picture with one we took in the Yucatan at http://www.backyardnature.net/n/10/101205rr.jpg.

The Latin genus name, Geococcyx, means ground-cuckoo, and it's true that roadrunners are members of the Cuckoo Family -- big ones reaching about two feet long (60cm) -- and that they spend most of their time on the ground. If you think about it, though, it's true that our roadrunner has a long tail with outer feathers boldly tipped with white, just like North America's Yellow-billed and Black-billed Cuckoos, plus it has a strong, down-curved beak like other cuckoos. An even more profound anatomical difference is that unlike the vast majority of other birds roadrunner feet bear two toes facing forward and two backwards -- their feet are "zygodactyl." A shot showing our Greater Roadrunner from the back displaying one of his zygodactyl feet is at http://www.backyardnature.net/n/13/130310rs.jpg.

Roadrunners prey on lizards, rodents, insects and even small birds. Their diet includes venomous spiders, scorpions and rattlesnakes. They've been seen working in pairs to overcome large snakes.

*****

POLYPHEMUS MOTH
Trundling down the dusty gravel road on the bike I kept my head low to avoid the dust a hard wind was kicking up and that's why I saw brown, papery wings being knocked about by the breezes. They were being held in place by the plump body and ground-clinging legs of the Polyphemus Moth, ANTHERAEA POLYPHEMUS, shown at http://www.backyardnature.net/n/13/130310mq.jpg.

Polyphemus Moths are members of the spectacular Giant Silkworm Family of moths, the Saturniidae, so already I knew the main points about their life history. For instance, that Saturniid moths like Polyphemus possess only useless, vestigial mouthparts and no digestive tracts, so they never eat. They simply emerge from their silken cocoons, females emit sex pheromones that can be detected by males well over a mile away (2kms), the male finds her using pheromone detectors in his oversized, featherlike antennae, they mate, the male promptly dies but the female flies away and lays her eggs, and then she dies too. Our Polyphemus was still alive, able to keep upright in the wind, but otherwise not moving at all.

I knew he was a male because his antennae were so large. From the battered, faded appearance of his wings and his lethargy, I guessed that either he'd already mated and now was dying, or maybe he'd been unable to find a female the night before, and now was simply running out of energy, and dying. You can confirm that really he has no mouthparts -- no coiled, strawlike proboscis like other kinds of moths and butterflies -- at http://www.backyardnature.net/n/13/130310mp.jpg.

After taking the above picture, when I returned our moth to the ground, he seemed unable any longer to hold his wings upright. He spread them across the ground, revealing his wings' eyespots, shown at http://www.backyardnature.net/n/13/130310mo.jpg.

The eyespots, which in Nature might frighten away a predator mistaking them for owl eyes, are responsible for the moth's name, for Polyphemus was the name of the giant, one-eyed Cyclops of ancient Greek and Roman mythology.

The Giant Silkmoth Family contains some of the world's largest and most colorful moths, and the Polyphemus is one of our largest moths, with a wingspan of up to 5½ inches (14cm).

I was a little surprised to see a Polyphemus Moth here because I associate them with humid eastern America. However, I read that local populations of them occur throughout subarctic Canada and the US. Their caterpillars feed on a large variety of plants, from pear trees to hickories, and that includes oaks such as our abundant Texas Liveoaks.

*****

GREEN CATERPILLARS IN THE MUSTARD GREENS
Picking mustard greens, a little green caterpillar about 15mm long (5/8ths inch) turned up beneath a leaf, with a single strand of silk anchored on the leaf's surface next to him and crossing his back, as shown at http://www.backyardnature.net/n/13/130310ca.jpg.

Volunteer identifier Bea in Ontario anguished over this one because there are so many little green caterpillars similar to this one. However, in the end she decided:

"I can't see it being anything else other than the Hawaiian Beet Webworm! But for some reason there are very few pictures on the internet. The host plant is wrong but in more than one website I've read that they will eat other plants if the regular host plant is not available."

Therefore: Hawaiian Beet Webworm, SPOLADEA RECURVALIS, so widely distributed throughout the world's warmer parts that its original home is uncertain. It occurs all across the US, mostly in the southern states. The caterpillar's preferred food is plants of the Amaranth Family, which includes beets, spinach and chard but, as Bea points out, when those foods aren't available it'll eat other things.

Bea wanted to see larger, more mature caterpillars to confirm that it was a Hawaiian Beet Webworm, so I returned to the mustard greens. All I found, though, was a caterpillar even smaller than the previous one, maybe 5mm in length (3/16ths inch), so small I couldn't see any features other than its greenness. However, I got a picture and sent it to Bea. That picture is at http://www.backyardnature.net/n/13/130310cb.jpg

Bea's reply, which only a true-blooded identifier could have sent, was:

"OH my gosh, Jim! That's the Diamondback moth caterpillar (Plutella xylostella)..."

So, the Diamondback Moth caterpillar is thought to be of European origin but now is found throughout the Americas and in Europe, Southeast Asia, Australia, and New Zealand. In North America the species has been recorded wherever cabbage is grown, and that sounds about right since around Uvalde during the winter there are vast, circular, irrigated fields of commercially grown cabbage. The caterpillars don't eat only cabbage, though; they feed on practically all members of the Mustard Family, which besides cabbage includes broccoli, Brussels sprouts, Chinese cabbage, cauliflower, collards, kale, kohlrabi, mustard, radish, turnip, and watercress.

******

ALMOST A MICROSCOPIC SNAKE
Exactly as the contents of this week's drop of water from the little Dry Frio River behind the cabin came into focus, a snake-like head thrust from an algae jungle across my field of vision, causing my head to jerk back as if I'd spotted a cottonmouth among water lily pads and not a microscopic entity among algae filaments quietly puddled on a glass slide. You can see the front end of my "snake" at http://www.backyardnature.net/n/13/130310bm.jpg.

Calming down and wanting to see how long the critter was I followed its segmented body backwards, looking for the tail. However, the body disappeared into a black tangle of algae and debris, though at the far end of the debris there emerged what surely was my snake's rear end, similarly segmented and mostly transparent, as shown at http://www.backyardnature.net/n/13/130310bn.jpg.

It's hard to say but I'm guessing that the "snake" was two or three millimeters long (1/8th inch). But, what was it?

The creature's leglessness, its segmentation, its mostly transparent body, and those bristles on its rear end first led me to think I might have a bristleworm -- a polychaete. However, no polychaetes were found with such rear-end bristles, and few polychaetes have eyespots.

Eventually I remembered how certain aquatic insect larvae possess such bristles so I began searching for images of larvae of very small insects I knew to hang about wetlands, and before long the right picture came up: I had the aquatic larva of a biting midge, also sometimes referred to as a no-see-um, midgy, sand fly, punky and by many other names. We're talking about those tiny, black things whose blood-sucking bites hurt all out of proportion to their miniscule size, and which in some areas near wetlands makes life miserable for people and other animals. Biting midges, of which many species are recognized, are members of the Biting Midge Subfamily, the Ceratopogoninae, with appears in the Fly Order, the Diptera. Biting midge larvae are mostly predaceous on other small aquatic animals, and themselves are eaten by animals larger than themselves, including small fish.

I can't find an explanation for our larva's rear-end bristles -- referred to as anal bristles by some -- but I have a theory about why they might be useful. The larva's body is stiffer than a snake's and thus can't undulate like a snake, whose coils propel the snake's body forward by pushing backwards against irregularities on the ground. However, the larvae's anal bristles might anchor the rear end of a larva among tangles of algae as the front end thrusts forward to attack prey.

*****

MESCALBEAN FLOWERING
Springy signs are everywhere. Each newly flowering plant is a joy to find, and maybe the best spring discovery this week was what's shown at http://www.backyardnature.net/n/13/130310ms.jpg.

There you see the first open flower of a raceme that should be very pretty once all its blossoms are open. This flower cluster was the only one atop a head-high, scrubby bush growing in thin soil atop a nearby limestone hill. We noted its woody-shelled legumes and bright red beans last October, when we identified it as the Mescalbean. You can see an opened pod from that time at http://www.backyardnature.net/n/12/121007ms.jpg.

It happens that this week my Estonian lady friend Malle went into Uvalde 35 miles to the south (56kms), and brought back a picture of a small tree resplendently blossoming with blue flowers, across from the town park, shown at http://www.backyardnature.net/n/13/130310mt.jpg.

That's also a Mescalbean, the same species. Since Uvalde is several hundred feet lower in elevation than us, spring there is more advanced than along the Dry Frio, and that accounts for all the flowers of the Uvalde tree's racemes being fully open. Also, growing in deep soil and probably being regularly watered, the Uvalde tree is much larger than ours and bears numerous racemes instead of the single one on our hilltop plant.

I'm glad to see a native plant being grown in town, and you can see why people like it. Mescalbean in flower suggests a tree wisteria. When Mescalbean trees are sold commercially and grown ornamentally, often they are called Texas Mountain Laurels. Being familiar with the real Mountain Laurel from the Appalachians back in Kentucky, it's hard for me to accept that name, however, since there's little about Mescalbean similar to Mountain Laurels, other than that it can be a small tree with many pretty flowers.

Mescalbean trees are especially good plants for gardens in droughty areas, though their seeds are very hard and tricky to propagate. They can withstand temperatures down to 10°F (-12°C).

*****

STONESEED FLOWERING
Also a little wildflower about four inches high (10cm) has begun flowering with its trumpet-shaped, yellow blossoms, as shown at http://www.backyardnature.net/n/13/130310li.jpg.

A view of the flower's face showing its crinkly corolla lobes and a pair of spherical stigmas at the mouth is shown at http://www.backyardnature.net/n/13/130310lj.jpg.

The English name most commonly associated with this pretty herb seems to be Narrowleaf Stoneseed, but it's also known as the Narrowleaf Gromwell, Fringed Puccoon, Narrow-leaved Puccoon and Plains Stoneseed. It's LITHOSPERMUM INCISUM, and it occurs across most of North America's central and western regions, into arid northern Mexico. It's described as preferring dry, sandy, clayey or loamy soils, but here I find it only on thin soil atop limestone rocks in the hills.

Narrowleaf Stoneseed is a member of the Borage or Forget-me-not Family, the Boraginaceae. One good field mark for that family is how the flowers' five stamens, which alternate with the corolla lobes, are inserted on the corolla tube, as shown at http://www.backyardnature.net/n/13/130310lk.jpg.

It's much more common for stamens to arise from below the ovary and not be affixed to the corolla like that.

The Navajo are reported to have chewed Narrowleaf Stoneseed root for coughs and colds. The plant's finely powdered leaves, root and stem have been rubbed on the body in the treatment of paralyzed limbs. An infusion of the root has been used for stomach aches and kidney problems. The plant has been eaten as an oral contraceptive, and a cold infusion of the pulverized root and seed has been used as eyewash.

*****

HENBIT
In lawns and along sidewalks and roads throughout North America Henbit is one of the earliest flowering, most common "weeds" announcing spring. I thought that maybe here it would be too arid for it, but on Thursday a two-inch-tall sprout developed its first blossoms in the grassy area next to the cabin, as shown at http://www.backyardnature.net/n/13/130310lm.jpg.

Henbit, a native of Eurasia and northern Africa, is LAMIUM AMPLEXICAULE, and it's a member of the Mint Family. Field marks confirming that it's a mint include its stem being square in cross section, its leaves occurring opposite one another on the stem, and its 5/8ths-inch long (15mm) flowers being "two-lipped" with definite upper and lower lobes. A close-up of the flowers is shown at http://www.backyardnature.net/n/13/130310ln.jpg.

Henbit can flower so early because it's a winter annual -- a plant that germinates in autumn, lives through the winter, and produces seed and dies the following season. This strategy gives it a head start on other plants whose seeds don't germinate until spring.

Despite Henbit being a mint, its herbage doesn't have a minty taste or smell. I know about the taste because sometimes I nibble on the leaves, which can be added to salads or used as a potherb. They're only about the size of a thumbnail, though, so you have to pick lots of them to get a mouth full. Basically the leaves have no taste at all, but in a world where you might be hungry someday and the landscape is populated mostly with plants with bitter or even toxic herbage, it's good to keep in mind the possibility of someday eating Henbit.

I wouldn't want to eat much of it, though, because the literature says that medicinally Henbit is "... antirheumatic, excitant, fever-reducing, laxative, stimulant, and has agents that induce sweating."

Henbit often grows alongside another weedy, spring-blooming species called Purple Deadnettle, Lamium purpureum. Purple Deadnettle has similar flowers and general aspect as the Henbit, but its leaves arise on petioles and are more clustered toward the stem's top. You can see that Henbit's leaves arise directly from the stem with no petiole.

*****

COCKLEBUR VARIATIONS
Along the banks of the little Dry Frio River behind the cabin Common Cockleburs with their leafless, dead stems still bearing burs produced last season can be seen, as shown at http://www.backyardnature.net/n/13/130310xn.jpg.

What draws my attention to these plants is that they are so tall -- about six feet (1.8m) and that their stems look and feel as woody as a small tree's. Cockleburs are annuals, though, and all the literature describes them as herbaceous.

The burs also are interesting because they're different from those I'm familiar with back in Kentucky and Mississippi. For example, a bur photographed in Mississippi is shown at http://www.backyardnature.net/n/09/090302cp.jpg.

You can compare that bur with one from a plant along the Dry Frio at http://www.backyardnature.net/n/13/130310xo.jpg.

The main difference is that the Dry Frio burs' long, hooked spines themselves bear tiny, stiff spines at their bases -- spines on spines -- while the Mississippi burs' spines have smooth, spineless bases.

Back in the 60s when I was learning my plants in Kentucky I had a hard time identifying our local cockleburs to species level because our plants didn't match the descriptions in the technical keys I was using, and there were many species to choose from. Nowadays it's a lot simpler, since nearly all the "species" I wrestled with back in Kentucky now have been lumped into one very variable species, the Common Cocklebur, XANTHIUM STRUMARIUM. The online "Integrated Taxonomic Information System" at http://www.itis.gov lists 38 previously recognized species and varieties now considered to be mere variations of Xanthium strumarium. Now the entire genus Xanthium is thought to comprise only two or three species.

So, generations of botanists huffed and puffed and worked themselves into a sweat trying to figure out cocklebur taxonomy. There were great debates and mighty pronouncements but, in the end, now that we can look at the genes, we see that all those variations on the cocklebur theme never could have been properly assigned to any of the taxonomic pigeonholes thought up for the plant -- except for the one labeled "it's all the same."

*****

FEATURED ESSAYS FROM THE PAST:

"Thoughts about Magic," from the July 7, 2002 Newsletter, at http://www.backyardnature.net/n/p/020707.htm.

"Thoughts beneath the Mesquite," from the September 21, 2007 Newsletter, at http://www.backyardnature.net/n/p/070921.htm.

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.backyardnature.net/n/.

Visit Jim's backyard nature site at http://www.backyardnature.net