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

June 22, 2014

HEAD COLORS OF MALE GOLDEN-FRONTED WOODPECKER
Earlier this month we remarked on the female Golden-fronted Woodpecker defending her nesting territory from her own reflection in windows at the house of my neighbor Phred. You can see that that female had both a yellow nape and yellow patches behind the beak -- yellow "nasal tufts" -- at http://www.backyardnature.net/n/b/centurus.htm.

Male Golden-fronted Woodpeckers display different color patterns, the patterns changing from subspecies to subspecies across the species' extensive distribution. Steve Howell adds in his A Guide to The Birds of Mexico and Northern Central America that the different subspecies are linked by "... variably intermediate populations."

Therefore, it can be interesting to know exactly what head-color pattern our male Golden-fronted Woodpeckers display. It happens that lately a couple of Golden-fronteds has been visiting our feeder, so you can see exactly what color pattern our local males display at http://www.backyardnature.net/n/14/140622gf.jpg.

The nape and nasal tufts are yellow, but the crown patch is red. This is the combination described as typical of the subspecies aurifrons, which is the subspecies occurring in the US and northern and central Mexico. Other subspecies display different patterns.

Despite this being what's expected for our subspecies, somehow it's gratifying to confirm that in our little corner of the woodpecker world head colors pan out exactly as advertised.

*****

SPHINX MOTH
Inside the screened-in veranda of the house I'm painting in the valley, a moth had entered where the doors had been removed and couldn't get out. Up close in early morning it looked like a tiny super-aerodynamic, delta-winged fighter jet resting on the tarmac between sorties, as shown at http://www.backyardnature.net/n/14/140622mt.jpg.

Though no mouth parts are apparent, the moth does possess a long, straw-like proboscis coiled below his head, used for sucking nectar from flowers. A picture more clearly displaying the conspicuous white band on the moth's abdomen is at http://www.backyardnature.net/n/14/140622mu.jpg.

This moth's thick body and large size -- this kind of moth often is confused with hummingbirds when visiting garden flowers at dusk -- plus its general shape, all suggest that he's a member of the Sphinx Moth Family, the Sphingidae, of which about 124 species are described for America north of Mexico.

With such distinctive markings volunteer identifier Bea in Ontario had little trouble deciding that our moth is the Titan Sphinx, also called the White-banded Day Sphinx, AELLOPOS TITAN, mostly found in the tropics from Uruguay and northern Argentina north through Central America, Mexico and the Caribbean, into the US, where it's established in the Florida Keys and the southernmost US states. Also, sometimes in late summer it ranges north as far as Maine and North Dakota.

Titan Sphinx caterpillars are large, juicy-looking hornworms that feed on members of the Madder Family, the Rubiaceae, of which here the most common species is the Buttonbush abundantly growing in and beside the little Dry Frio River.

A striking feature of our Titan Sphinx is the two-toned tuft of stiff hairs at its rear end, a close-up of which is at http://www.backyardnature.net/n/14/140622mv.jpg.  

These hairs are known collectively as the hair-pencil, and they can be spread to provide more surface area to the air, for releasing pheromones, or sexual hormones, released from the moth's rear end. Both male and female Titan Sphinxes have them.

Not all mothsbear hair-pencils but the males of species that do may use their hair-pencils to sprinkle pheromones right onto the female's antennae. This appears to have such an overwhelming effect on the female that not only is she roused sexually but also she becomes incapable of flying away. In certain lepidopterous species the pheromones thus sprinkled also keep other males away.

Bea submitted our pictures to ButterfliesAndMoths.Org where it's always gratifying to see our IDs confirmed, and our information made available to the rest of the world. You might enjoy seeing that website's page featuring our pictures at http://www.butterfliesandmoths.org/sighting_details/979373.

On that page the species name Aellopos titan is linked to another page providing basic life-history information about Titan Sphinxes and, toward the page's bottom, a map showing where confirmed sightings have originated. If you click on the westernmost large, orange dot in Texas you can see that that's our report. How about that?

*****

MOSQUITO LARVAE & PUPAE
On Juniper House's deck I keep a dishpan filled with water, with a large rock in its center. That's my birdbath, where birds drink more than they bathe, though sometimes a brave individual will indeed hop onto the rock and dip and flutter until water is splashed everywhere.

If I don't change the water frequently it develops a healthy population of what as a child in Kentucky I called "wiggletails." Wiggletails were immature forms of mosquitoes. A wiggletail suspended in water scooped from my birdbath and held in a glass jar is shown at http://www.backyardnature.net/n/14/140622wu.jpg.

The dark item at the top, the larva's "tail," is its air tube. Most of the time wiggletails rest just below the water's surface, drawing air into their bodies through their air tubes. Just below the air tube and to the left, forming a right angle with the air tube, is the "saddle" bearing groupings of hairs known as "tufts." Tufts are thought to help stabilize the larva in the water. Their position on the saddle and their appearance is important in mosquito larva identification.

You'll notice that on the larva there are no fins to propel it through the water. It moves fairly inelegantly but effectively by jerking its entire body. Mosquito larvae spend most of their time feeding on algae, bacteria, and other microbes at the water's surface.

As a kid I knew that wiggletails turned into mosquitoes, because on the farm we collected rainwater for washing clothes and other things, and our rain barrels were always wiggletail heavens. Despite this early education, later in school when I tried to fit what I'd seen with my own eyes with what I was learning about insect metamorphosis, I ran into a problem. Namely, what about mosquito pupae?

For, like butterflies, beetles, flies, ants and some other insect types, mosquitoes undergo complete metamorphosis, which involves these stages:

EGG --> LARVA --> PUPA --> ADULT

So, where did the mosquito's pupal stage take place, what did it look like, and how had I missed it? This week my birdbath was full of mosquito pupae, and this time I knew what they were. You can see their black, comma-shaped forms floating at the water's surface at http://www.backyardnature.net/n/14/140622ws.jpg.

I must have seen these as a kid, but thought they were something else. A Juniper House pupa was dipped up with a spoon and looked at with our dissection scope, so you can see what a mosquito pupa up close looks like at http://www.backyardnature.net/n/14/140622wt.jpg.

In that picture the large, oval section on the right is the cephalothorax containing the future mosquito's head and thorax. A closer look at the cephalothorax is provided at http://www.backyardnature.net/n/14/140622ww.jpg.

The dark spot at the cephalothorax'sfront is an eye. The pair of small, winglike objects atop the cephalothorax's hump are "trumpets," which the pupa breathes through when resting at the water's surface. If you look closely behind the eye you can see the future mosquito's developing wings and their veins pressed against the cephalothorax's surface. Forming legs also are visible. A close-up of the pupa's other end, the tip of its abdomen, is shown at http://www.backyardnature.net/n/14/140622wv.jpg.

The two semitransparent, fanlike items at the abdomen's tip are "paddles" used for moving through the water. Like the larvae, pupae also swim with violent jerks, in some places earning them the name of "tumblers." Unlike the larval stage, mosquito pupae don't eat. Most of the time pupae simply float at the water's surface while enormous physiological changes occur within them in preparation for their metamorphosis into adult mosquitoes.

A point not to miss here is that the mosquito's pupae are highly mobile. So often insect pupae we encounter -- such as the butterfly's chrysalis, moth pupae overwintering in cocoons, and shell-like puparia of flies -- are immobile, so it's easy to develop the false notion that no pupae are capable of traveling about.

*****

ORCHID AMAZEMENT
This week, right below Juniper House, a flowering plant turned up that might qualify as the most interesting wildflower discovery made during my time here. It's something I've seen nowhere else, and which any botanist familiar with the Texas flora would get excited about. You can see it in all its 15-inch-high splendor (38cm) at http://www.backyardnature.net/n/14/140622hx.jpg.

It's an orchid unlike anything listed for this part of the Edwards Plateau, and I was flabbergasted to see it right at Juniper House's doorstep. Note that no leaf is associated with the flowering stem. Each blossom is associated with a small, triangular "bract" arising where the flower attaches to the stem, but these are not leaves. This is one of that small minority of orchid types that produce no leaves at all, and no chlorophyll, because it's saprophytic, meaning that it obtains food from dead organic matter, made possible by the orchid's symbiotic relationship with a fungus. This orchid doesn't photosynthesize its food like the vast majority of flowering plants.

A flower close-up is at http://www.backyardnature.net/n/14/140622hy.jpg.

Along with the Composite or Daisy Family, the Orchid Family is one of the two largest of all flowering plants. Though most orchid species occur in the tropics, the Flora of North America treats 208 orchid species in 70 genera occurring in North America.

During our orchid's identification process, the lack of leaves and chlorophyll eliminates the vast majority of candidate species our orchid could be. The flower disqualifies quite a few other possibilities simply by being so large -- about 1.5 inches (4cm) -- pink, and by not bearing a "spur." A flower's spur is a conical appendage projecting backward, and containing nectar for enticing pollinators to visit. A shot of a flower from the front shows other field marks enabling us to identify the plant with certainty, at http://www.backyardnature.net/n/14/140622hz.jpg.

Important to notice here is that the darker-pink lower part, the "lip," is deeply three-lobed, with a pale center, and the low ridges running through the white zone are not colored, but rather are white.

So, or orchid is known variously as the Largeflower Crested Coralroot, Giant Coralroot, and by other names. It's HEXALECTRIS GRANDIFLORA, found from southern Mexico to the north, but in the US, according to the Flora of North America found only in far western Texas, in the Big Bend area -- in the Davis and Chisos Mountains. In other words, this orchid is not supposed to be here...

I sent our photos to Dr. Tom Wendt, Curator of the Herbarium at The University of Texas at Austin, who confirmed the ID, and remarked that this is "a really great and interesting find." And despite what the Flora of North America says, Dr. Wendt also mentions two other fairly recent discoveries of the species outside the Big Bend area, near Austin and Dallas. "Your find helps fill in the huge gap between those two localities and the Trans-Pecos," he says, the Trans-Pecos being the region in Texas west of the Pecos River -- Big Bend.

Dr. Wendt isn't sure why suddenly the species is showing up far beyond its historically known boundaries. One thought is that maybe now that fewer livestock are roaming the hills eating everything in sight, orchids may be returning. One problem with that idea is that in our area we have a gross overpopulation of deer who also eat orchids.

Dr. Wendt wanted a voucher specimen but was sensitive to the problem of collecting the only plant known to exist in the region, so he asked for a single flower, pressed and dried, which as been provided. Eventually the Flora of North America may have the proof it needs to update its distribution information for the beautiful, mostly tropical Hexalectris grandiflora.

*****

VELVET BUNDLEFLOWER
In beat-down, tall grass along the one-lane gravel road up the Dry Frio Valley a smallish, low-growing plant with ferny leaves and powderpuff-like clusters of white flowers sprawled atop the grass, as shown at http://www.backyardnature.net/n/14/140622ds.jpg.

Serious flower sniffers, seeing those ferny leaves and powderpuff-like clusters of flowers, immediately recognize not only that our plant is a member of the big Bean Family, but also of the Mimosa Subfamily, the Mimosoideae. Besides mimosas, well known members of that subfamily include acacias and Silktrees (Albizia), both with ferny leaves and powderpuff inflorescences. Our plant confirms its membership in the Bean Family by producing the two-inch-long (5cm), legume-type fruits shown at http://www.backyardnature.net/n/14/140622dv.jpg.

A closer look at our plant's mimosa-like leaves, which are compound, with tiny leaflets, plus the flower cluster, is at http://www.backyardnature.net/n/14/140622dt.jpg.

A twice-divided, or "bipinnate," leaf showing how heavily invested our plant is with short, soft hairs, giving it a velvety appearance and feeling, is shown at http://www.backyardnature.net/n/14/140622dw.jpg.

A closer look at a cluster of flowers is at http://www.backyardnature.net/n/14/140622du.jpg.

Here you see eight or so tiny flowers closely clustered in the head's center, each flower with a purple-tinged calyx and greenish corolla, from which arise ten stamens composed of long, white filaments topped with oval, yellow anthers. Something unusual about this flowering head is that below the cluster of stamen-producing flowers there's a ring of several other flowers, but these are held horizontally and the white filaments issuing from each flower are much longer than those of the central flowers, and bear no yellow anthers. These flowers forming a fluffy, white "collar" for the flowering head are sterile, apparently serving to better attract pollinators.

Though a mind-boggling number of Bean Family plants occur in Texas, only a small fraction of those are member of the Mimosa Subfamily. Shinners & Mahler's Illustrated Flora of North Central Texas includes only six genera, a number the mind can handle.

Among Texas' s Mimosa Subfamily members, our roadside plant's genus quickly identifies itself with three easy-to-see field marks: Plants are not woody; they bear no spines, and; their flowers are white. The genus is Desmanthus, whose species often are known as bundleflowers.

In our area we might conceivably encounter seven or so Desmanthus species. Desmanthus is mostly a Mexican genus (14 species), so, being so close to Mexico, that explains why we have so many species.

Our Desmanthus easily distinguishes itself from the other possible species because of its conspicuous, velvety hairiness. Some other species may have a few hairs, but nothing compared to our species' covering.

Our roadside species often is known as the Velvet Bundleflower. It's DESMANTHUS VELUTINUS, mostly occurring in northern Mexico, but in the US found in southern Arizona, New Mexico and much of Texas. Typically it occurs on slopes with limestone or caliche soils. The road where the plant occurred was on limestone.

Velvet Bundleflower is a useful species, its spineless leaves and stems being eaten by various grazing animals, and birds such as quail eating its seeds. Its seeds often are included in seed mixes used for range improvement.

*****

BERMUDA GRASS
Along an isolated part of the little one-lane gravel road running up the Dry Frio Valley a certain smallish, foot-tall grass was flowering, its heads of the kind with its branches spreading like toes on a turkey foot. It's shown at http://www.backyardnature.net/n/14/140622bg.jpg.

North Americans are very familiar with grasses looking more or less, or exactly, like this, since both crabgrass and Bermuda Grass -- invasive weed-grasses in lawns and other much-disturbed areas -- produce flowering heads similar to these. So, which was this? Or was it something else entirely?

At http://www.backyardnature.net/n/14/140622bh.jpg a close-up of one of this grass's flowering heads, or inflorescences, shows an important field mark. That is, that the spike-like branches all arise together exactly at the tip top of the inflorescence stem, or peduncle. Bermuda Grass inflorescences do this, but usually -- but not always -- crabgrass' s don't. Crabgrass's spike-like inflorescence branches arise near one another atop the peduncle, but not exactly at the tip. You can see Crabrass's inflorescence at http://www.backyardnature.net/n/h/crabgrss.htm.

So that's a vote for Bermuda Grass, or something very close to it, but Crabgrass isn't completely eliminated yet.

A close-up of how the individual spikelets are arranged on just one side of the flattened, spike-like branches is at http://www.backyardnature.net/n/14/140622bi.jpg.

In that picture the flowers are at their sexual peak, the pale pinkish, oblong items dangling on slender, white filaments being the anthers releasing their pollen, while the fuzzy, dark, raspberry-colored things are stigmas of the female parts, reaching into the air for pollen.

You can see that this species' ligules -- the low, wall-like barrier where the leaf meets the stem, which may or may not be present, and which takes many forms -- is hairy, at http://www.backyardnature.net/n/14/140622bj.jpg.

Crab Grass's ligule is "membranous," which means that it's like a low, cellophane-like collar. It may or may not be hairy. However, the important point is that Bermuda Grass's ligule consists only of hairs. So at this point we can discard Crab Grass as a candidate.

Actually, we don't have to look for such a tiny detail to be convinced that we don't have Crab Grass, and you can see why at http://www.backyardnature.net/n/14/140622bk.jpg.

Our roadside grass's stems arise from a tough stolon -- in this picture the stolon being the stiff stem pointing toward the picture's top, right corner. Stolons can be thought of as stems that lie on the ground, often rooting at nodes where leaves may arise. Having such a stolon snaking across the ground, we see that our grass is a perennial. Crab Grasses are annuals with no such stolons.

So, this is indeed Bermuda Grass, CYNODON DACTYLON, native to the Middle East, not Bermuda, though it may have been introduced into the US from Bermuda where it arrived first. About five Cynodon species, all invasives, occur in North America, but Cynodon dactylon is by far the most common.

City folks with obsessions for monocultured, manicured lawns dislike Bermuda Grass because it is aggressive and can push neater-looking, gene-jangled turf cultivars aside. However, much of the world is grateful to Bermuda Grass because, at least in warm places, it makes good grazing for livestock where other grass species can't thrive. In California they've even shown that Bermuda Grass irrigated with salty water produces good forage for cattle. In fact, several Bermuda Grass cultivars have been produced providing humanity special services, and as global warming works its magic, in the future in certain areas Bermuda Grass may come to be regarded as a kind of savior.

*****

FEATURED ESSAYS FROM THE PAST:

"Cloud Watching" from the August 3, 2007 Newsletter, at http://www.backyardnature.net/n/p/070803.htm

"Comforting Visions of Vultures & Maggots" from the January 25, 2004 Newsletter, at http://www.backyardnature.net/n/p/040125.htm

*****

Best wishes to all Newsletter readers,

Jim

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