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

August 17, 2014

HOUSEFLY
|Early one morning as I arrived at the house I was painting, I noticed a black dot on the house's old, white siding. Thinking it was a nail head needing to be pounded in before I painted, two mating flies almost got smushed before I realized what they were. You can see them at http://www.backyardnature.net/n/14/140817fl.jpg.

They looked like houseflies, and they were even on a house, but there's a whole world of flies that look like the species normally called Houseflies. So, were these flies "real" Houseflies? Figuring that out can be more of a challenge than you might think. The Housefly Family, the Muscidae, embraces around 4500 described species worldwide (about 700 in North America) in about 180 genera, and at first glance the vast majority of those species look pretty much like the flies in our picture.

After slogging through all those species comparing technical features, here's my semi-technical advice on how to know whether you have a "real" Housefly, MUSCA DOMESTICA, which, by the way, our black dot on the house siding turned out to be.

The most definitive field mark for the Housefly is the last one. A technical paper describes that point as a "sharp upward bend in the fourth longitudinal wing vein." One common species often misidentified as a Housefly is the Stable Fly, Stomoxys calcitrans, but the vein crossing the same area in its wing is only slightly curved, not pointed like the Housefly's. The Lesser Housefly, Fannia canicularis, also looks very similar and is common, but it is somewhat smaller and its vein in that part of the wing is straight, not at all forming the sharp angle.  Around here we have lots of Face Flies, Musca autumnalis, which also are very similar. You like to look for that harp angle in the wing of a local Face Fly at http://www.backyardnature.net//n/a/facefly.htm.

It's almost mysterious that Nature should present us with such similar-looking flies who differ so drastically in this single, somewhat obscure feature.

At one time or another all of us hear how Houseflies might fly directly from a pile of dog poop onto the sandwich you're eating, and in so doing deposit onto your food untold numbers of illness-causing microbes. That's true, and it's not encouraging that the Housefly's immature larva, its maggot, spends its days burrowing through decaying garbage, carrion or feces.

A single female Housefly can lay approximately 9,000 eggs in a lifetime. As such, one pair of flies can produce more than 1 million offspring through their offsprings' offspring in a matter of weeks. Obviously, the vast majority of Houseflies must be preyed upon fairly quickly, by spiders, praying mantises, dragonflies, swallows and the like. Therefore, houseflies provide an important service in Nature, and their maggots' lusty conversion of decaying material also is an important role, Houseflies normally live for two weeks to a month.

*****

CATALPA
Along a backstreet in Uvalde a tree stood out simply because it wasn't a liveoak. It bore large, heart-shaped leaves clustered at the tips of its thick branches, and long, slender, capsular-type fruits dangled from among them, as seen at http://www.backyardnature.net/n/14/140817ct.jpg.

This is one of my favorite trees, if only because back on the farm in Kentucky where I grew up it was so common in people's backyards, and along roads and trails, despite its being disdained as a weed tree. Its wood was despised as too likely to warp and splinter, and it wasn't much good for burning. However, the hand pegs we used for setting our precious tobacco plants were carved of catalpa, probably because the wood could be whittled into peg form so easily. Back then, the main reason people kept Catalpas around their houses was that for several months of each summer the leaves hosted legions of large, juicy caterpillars that made great bait when fishing for catfish in local ponds. We never called our trees Catalpa, however; in our Western Kentucky speak, it was Patalfa, or maybe even Pataltha, according to my mother.

Two look-alike Catalpa species are native to the US. The Northern Catalpa, Catalpa speciosa, is home from Illinois through Kentucky to Tennessee and Arkansas, while the Southern Catalpa, Catalpa bignonioides, is native from Florida through the Gulf states, to Texas. The Northern produces noticeably larger leaves and flowers than the Southern. Both species have been widely planted and spread far beyond their range; there used to be one featured in a garden near where I lived in Belgium.

Catalpas are members of the large but mostly tropical Bignonia Family, the Bignoniaceae, the best-known members to North Americans probably being the woody, viney Trumpet-Creeper and Cross-Vine. Members of the family normally produce large, pretty flowers with tubular corollas, and longish fruit capsules that split at maturity to release small seeds that often bear papery wings, which help the seeds disperse on the wind. Catalpas display all these Bignonia Family field marks.

When I saw the one in the picture, in Uvalde, it struck me that its leaves seemed smaller than I remembered. That would make sense if the ones on the farm in Kentucky were the Northern species native to that area, and the one in Uvalde were the Southern species, native to eastern Texas but not this far west.

On that shaky basis, I'm guessing that the species in our picture is the Southern Catalpa, CATALPA BIGNONIOIDES.

The tree in Uvalde wasn't doing well. Some of its larger branches were dying back, apparently from the drought. I looked for "patalfa worms," as I called them as a kid, but saw none. Still, it was a real pleasure seeing a Catalpa in Uvalde.

*****

MILKWORT
On an almost-vertical cliff face along the Dry Frio river, rooted in what seemed to be solid, marly-limestone rock, a mere sprig of a wildflower only about six inches tall (15cm) somehow was surviving the current drought, and even blossoming. You can see it with its leaves about 10mm long (3/8ths inch), and purple, branch-tip flowers at http://www.backyardnature.net/n/14/140817po.jpg.

In that picture notice the dead, decaying stems from previous years slumped below the plant, informing us that this is a perennial. A close-up of a flower is at http://www.backyardnature.net/n/14/140817pp.jpg.

Another flower shown from the side appears at http://www.backyardnature.net/n/14/140817pq.jpg.

At first glance, because of the flower's two-lipped (bilaterally symmetrical) corolla, the plant struck me as one of those members of the Bean Family in which the Bean Family's normally compound leaves have been reduced to a single leaflet. However, up close the flower didn't look like a typical "papilionaceous" bean blossom, plus the Bean Family's stipules -- tiny, leafy flanges at petiole bases -- weren't apparent. Also, that thick, greenish item in the flower's center didn't make sense. Apparently this wasn't a Bean Family member.

Last December we encountered a similar small perennial similarly growing on a bank of the Dry Frio, and at that time we went through the same thought process beginning with the Bean Family. Ultimately that plant revealed itself as a member of the Milkwort Family, the Polygalaceae, closely related to the Bean Family. So, back at the computer it was a simply matter to see whether another member of the Milkwort Family might occur in Uvalde County, and such was the case.

In books and on the Internet our plant often is referred to as the Shrubby or Purple Milkwort, POLYGALA LINDHEIMERI. For the pleasure of experiencing a "variation on the milkwort theme," you might enjoy compare our present Purple Milkwort with the one found last December, the Eggleaf Milkwort, at http://www.backyardnature.net/n/h/polygala.htm.

Our Shrubby or Purple Milkwort occurs in Texas, southern New Mexico and Arizona, and adjacent northeastern Mexico. Little is known of this plant found in such a limited area, but it seems to favor limestone.

In 2009, J. Richard Abbott did his PhD dissertation at the University of Florida on the Milkwort Family, the Polygalaceae. Sequencing the genes of various species in the family, he discovered that the big genus Polygala consisted of quite a number of similar looking species that were not too closely related. He broke up the genus, so that today both the Polygalas found in Uvalde County no longer Polygalas. The Eggleaf Milkwort found last December is now Hebecarpa ovatifolia, and our present Shrubby Milkwort is Rhinotropis lindeimeri.

However, at this time most web pages and printed field guides continue to list them both as members of the genus Polygala, and both are referred to as milkworts.

If you'd like to see what the dissertation looks like that has so mangled the comfortable old genus Polygala, it's downloadable for free at http://etd.fcla.edu/UF/UFE0041138/abbott_j.pdf.

*****

WATER-WILLOW'S EXPLOSIVE, UPSIDE-DOWN VIOLINS
At this location we've profiled several members of the Acanthus Family, the Acanthaceae: the Mexican Honeysuckle; Wild Petunia; Torrey's Wrightwort; Water-willow, and; Hairy Tubetongue. Normally in our discussions of these species it was said that an important field mark for the Acanthus Family is that its mature fruits typically are shaped like plump, upside-down violins, with their slender necks issuing from a cuplike calyx.

Around here the most commonly occurring member of the family is the Water-willow, often forming dense stands in sometimes-submerged stretches of the Dry Frio River. You can see Water-willows doing just that on our Water-willow page at http://www.backyardnature.net/n/h/justicia.htm.

When pictures on that page were taken, the Water-willows were flowering. Nowadays, later in the season, when the vast majority of plants emerge from a bone-dry bed, a few plants bear fruits, but mostly they bear neither fruits nor flowers. You can see a Water-willow's split-open fruit at http://www.backyardnature.net/n/14/140817ww.jpg.

To appreciate the fruit's upside-down-violin form you must visualize the fruit before it split, so that the V-shaped split fruit becomes a slender neck arising from the green calyx, with the neck greatly bulging at the top. You can see a similar fruit, before it split open -- and one with a bug-eaten hole in it -- of the Torrey's Wrightwort at http://www.backyardnature.net/n/13/130915ad.jpg.

Why is our Water-willow's fruit split so strangely? It's because when the fruit, a capsule, is mature and conditions are right, the fruit snaps open explosively, sending seeds flying for several feet. The capsule's upside-down violin shape, then, is understandable because the farther away a seed can be from the calyx, the more momentum it can have when the capsule splits, and the farther away it can be lung. In our Water-willow fruit, one seed remains because its interior has been devoured.

In general appearance, the Torrey's Wrightwort and Water-willow plants are very unlike one another, yet you can see that their upside-down violin fruits are very similar. Some plant families, such as the big Rose Family, produce fruits in a huge variety of forms, but the Acanthus Family seems to love its explosive, upside-down violins.

*****

MILLET
Earlier this month we looked at a Milo grass plant, Sorghum bicolor, that "volunteered" where birdseed from Juniper House's feeder fell into a pot of Aloe vera. Our page taking a close look at that Milo is at http://www.backyardnature.net/n/h/milo.htm.

This week yet another non-native, large-grained grass turned up in another pot below the feeder, near the Aloe vera, this time cohabiting with some Basil, as shown at http://www.backyardnature.net/n/14/140817mi.jpg.

A closer look at the flowering head, or inflorescence, is at http://www.backyardnature.net/n/14/140817mj.jpg.

For identification purposes, an important field mark seen in that picture is that the grass's spikelets arise at the ends of slender pedicels, which arise from branches of the inflorescence, which themselves branch from other inflorescence branches. In other words, this is a panicle-type inflorescence. Milo's flowering head also is a panicle, but Milo's flowers are much larger than these -- up to 9mm long (3/8ths inch), while these are only about half that long, 4.5mm long (3/16ths inch) . A close-up of individual flowers, or spikelets, with the middle spikelet exhibiting a mature, shiny, white grain, and with each spikelet appearing to be subtended by three substantial scales, or glumes, instead of the normal two, is at http://www.backyardnature.net/n/14/140817mk.jpg.

The "three glumes" below each spikelet is important for identification purposes, and can contribute to confusion when "keying out" the grass using technical keys. In reality, each spikelet just has two glumes, as it's supposed to, but its "lemma" -- which in a "normal" grass floret is much less conspicuous and more closely enveloping the grain --in this genus looks like a "third glume."

Another sure indication that our Basil-pot grass is not just a stunted Milo is that the Milo plant's stem is hairless, while the Basil-pot grass's is long-hairy, as shown at http://www.backyardnature.net/n/14/140817ml.jpg.

From the beginning I suspected that our Basil-pot grass was Millet, since the bag the birdseed came in says it contains "White Millet, Milo, Wheat, Cracked Corn, Black Oil Sunflower." However, several grass species in entirely different genera are known as millets, and the seed bag's name "White Millet" also is a little ambiguous, so we still need to do some botany to be sure of which millet we have.

With the panicle-type inflorescence, with each spikelet containing just one fertile flower, and with spikelets being on long pedicles, our Basil-pot grass soon reveals itself as a member of the big, important grass genus Panicum.

Among the Panicums, of which maybe 30 or so occur in North America, our plant with its exceptionally large glumes, lemmas and grains soon reveals itself as PANICUM MILIACEUM, which is one of the several species known as millets. Besides being known as just plain Millet, it's also known by the names Common Millet, Proso Millet, Yellow Hog, Grain Millet, Broom Corn Millet, Hog Millet, and our seed-bag' White Millet. Among the various species known as millet, it's the third-most planted, the most popularly grown millet being Pearl Millet, Pennisetum glaucum. With such a proliferation of names for this single species, and these various names often shared with other species, one is especially glad for the binomial Panicum miliaceum.

Panicum miliaceum's wild ancestor lived in Eurasia and, as was the case with Milo, and has been grown by humans for a long time ago. Its earliest domesticated remains have been excavated from sites occupied by humans about 7,000 years ago. These early site ocur in both the southern Caucasus Mountains and China, suggesting that the species may have been domesticated independently in each area. It's still extensively cultivated in India, Russia, Ukraine, the Middle East, Turkey and Romania. In the United States it's mainly grown for birdseed, but it's also sold as a health food. Due to its lack of gluten, it's marketed as a starchy food for those who can't tolerate wheat.

Our Basil-pot Millet is much smaller than Panicum miliaceum plants grown commercially, which normally reach about four feet high (1m), and whose heads may contain hundreds of whitish grains, instead of our plant's 15 or so. Our plant had to compete with a robust Basil plant. Still, despite its retarded growth, it displays very well all the distinguishing features of Panicum miliaceum.

*****

WALNUT WART GALL
Nowadays warty-looking galls are turning up on the leaves of several plant species. You can see some on the leaflets of our Little Walnut, Juglans microcarpa, at http://www.backyardnature.net/n/14/140817ga.jpg.

A closer look, showing that the small galls are covered with hairlike trichomes, is at http://www.backyardnature.net/n/14/140817gb.jpg.

It can be hard to identify the agents that cause particular kinds of galls to form. However, often the organisms causing galls restrict their activities to just one or a few species of host plants. Keeping that in mind, and noticing that these galls resemble warts, on the Internet I did an image search on the keywords "gall walnut wart," and within seconds was presented with pictures matching ours. They were attributed to "Walnut Gall Mites," Eriophyes erinea. Unfortunately, all the matching pictures were taken in Europe and I find no reference to Eriophyes erinea occurring in the Americas.

Still, it's a good guess that our Little Walnut's warty galls are caused by mites in the same family at Eriophyes erinea, and that's the Eriophyid mite Family, the Eriophyidae. Since we're talking mites here, we're referring to arachnids, like spiders, not insects.

The Eriophyid Mite Family is huge, with more than 200 genera and 3600 known species, but it's estimated that these known species account for only about 10% of the world's actual number. The family is poorly studied, so it's entirely possible that our galls on a walnut species found only in the US south-central states and northeastern Mexico might be caused by a mite unknown to science, or at least poorly documented.

Members of the Eriophyid Mite Family are microscopic, and yellow to pinkish white to purplish in color. I think of mites as looking like tiny spiders, but Eriophyid mites are worm-like or cigar-shaped, with only two pairs of legs (most mites have four pairs). They're so small that they disperse mainly on the wind. They occur on a wide range of plants, and several species cause serious crop damage. Most species are very host-specific -- so you wouldn't expect to find a single species forming galls on both walnut and apple trees.

Eriophyid mites feed deep within a plant's tissues, sucking out plant juices. As they feed, they introduce into the plant tissue a toxin that causes deformation of plant growth -- a tumor-like gall.

On the Internet I find galls looking like ours produced by the Eriphyid genus Aceria, of which over 900 species are known, many of which occur in the US. Otherwise, I can't say much more of the warty galls on our local Little Walnuts than that they appear to be caused by Eriophyid mites.

Still, I bet that someday a specialist will be tickled to see our documentation, and maybe he or she will write, saying exactly what we have here.

*****

FEATURED ESSAYS FROM THE PAST:

"Living without A Refrigerator" from the April 7, 2007 Newsletter, at http://www.backyardnature.net/n/p/070407.htm

"Our Electricity Goes Out" from the April 7, 2008 Newsletter, at http://www.backyardnature.net/n/p/080407.htm


*****

Best wishes to all Newsletter readers,

Jim

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