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

May 18, 2014

FIRE ANTS HERDING APHIDS
The freshly sprouted stem of a shrubby Roosevelt Weed, Baccharis neglecta, bore hundreds of tiny, green, sap-sucking aphids being attended by ants. Certain ant species feed on the sweet, carbohydrate-rich "honeydew" produced at the rear ends of feeding aphids, and sometimes protect and move the aphids around. I've been wanting to identify the ants that do that there, so I began taking pictures of these on the Roosevelt Weed, one of which is shown at http://www.backyardnature.net/n/14/140517an.jpg.

The strange items covered with white, blunt projections are addressed in the next section. Here we just want to get oriented, noting the particularly small, green aphids, sometimes with a pinkish tinge, and the ant's general shape and coloration. A side-shot of the ant better showing its structure is at http://www.backyardnature.net/n/14/140517ao.jpg.

When the disturbed ant in the picture reared its black rear end as shown, it occurred to me that this was just like a fire ant threatening to sting, but I'd never heard of fire ants herding aphids. However, when the above picture came onto the laptop showing the small, black eye on the reddish head, and the double-jointed arrangement of the ant's middle section, it looked even more like a fire ant. As I refreshed my memory of exactly what a fire ant looks like, I grew more and more convinced that this aphid-herding ant was indeed a fire ant.

On the Internet a Texas A&M page turned up declaring that in fact invasive Red Fire Ants do indeed protect and manage aphids, and the extra energy the ants derive from the aphids' honeydew " ... gives them the energetic edge needed to out-forage native species and conquer new territory."

In Argentina, where fire ants are from, many native ant species out-compete fire ants for aphid honeydew, so fire ants take only about 2% of the honeydew produced. In the US, however, fire ants are much more successful, controlling over 75% of a specific area's honeydew supply. The Texas A&M article can be accessed here.

Fire ants arrived this far west in Texas only within the last few years. Local old folks just shake their heads when the speak of the way the ants' arrival has devastated populations of ground-nesting birds, especially bobwhites and meadowlarks, who used to be abundant here, but now are very rare. The same is said about horned lizards ("horny toads"). I'm told that they used to be abundant, though I've not seen a single one since arriving, except for one squashed on a street in Uvalde. Here I find fire ant numbers to be only a tiny fraction of what I experienced in southwestern Mississippi. I seldom get stung, and only occasionally see a nest.

*****

APHID-SIZE CATERPILLARS WITH WHITE SPINES
While photographing ants collecting honeydew from aphids on the freshly sprouted stem of a shrubby Baccharis neglecta, something white was present among the aphids, but I couldn't imagine what it was. The aphids themselves were smaller than those who infested my mustard greens last winter, so the white things were tiny. You can see two of them at http://www.backyardnature.net/n/14/140517ap.jpg.

Only when I got that picture on the laptop screen could I see what an extraordinary find we'd made. Was it an aphid or a miniscule caterpillar infested with cocoons of parasitic wasp pupae, such as the braconid wasp cocoons shown on our page at http://www.backyardnature.net/n/a/braconid.htm?

Or was it an aphid-size caterpillar or some other kind of incredibly small insect adorned with blunt, white spines?

Sending the picture to volunteer identifier Bea in Ontario, it wasn't long before an email shot back saying that largely by chance she'd stumbled upon pictures matching our mystery entity, and that what we have is the larva of a ladybird beetle of the subfamily Scymninae.

Both adult and larval ladybird Scymninae are known to feed mostly on scale insects but also eat aphids and mealybugs. Scymninae larvae, as we see, are covered with waxy white tufts, causing them to resemble certain caterpillars or mealybugs themselves, evoking the expression, "wolf in sheep's clothing."

Numerous Scymninae larvae are similar to ours and we couldn't more precisely pin down our lavae's identity, so Bea submitted the picture to BugGuide.Com to see if someone more expert could carry it further. Abigail Parker in Philadelphia, describing herself as a passionate entomologist focusing especially on ladybird beetle larvae, soon remarked that with just a picture she couldn't be more precise than to say it's probably in the tribe Scymnini -- a subdivision of the subfamily Scymninae. Beetles in that tribe are known as Dusky Lady Beetles, and six genera of the tribe are known to occur in North America north of Mexico. They're small, dark beetles, less than 3mm long.

Abigail also pointed out that our larvae's body color showing beneath the white cocoons is yellowish, which would further help us narrow down the possibilities, if only anyone knew which genera or species the yellow-bodied ones metamorphose into. She's also seen gray- and pink-bodied ones.

*****

YELLOW HEX ON A WALL
I was scraping an old house's weatherworn, exterior walls in preparation for painting when an exceptionally large, yellow mayfly turned up clinging to a plank, shown at http://www.backyardnature.net/n/14/140517mf.jpg.

The mayfly's presence there made sense because the house perched at the very edge of a cliff overlooking the little Dry Frio River where about a foot of water was pooled. The mayfly didn't seem interested in moving so an interesting photo was possible, showing the creature with its front legs curiously thrust upward, seen at http://www.backyardnature.net/n/14/140517mg.jpg.

Volunteer identifier Bea in Ontario recognized this as a member of the genus Hexagenia, and when I looked into what species it might be, it seemed that the only Hexagenia species that might occur this far west is one known as the Hex, HEXAGENIA LIMBATA.

On the Internet, many pictures of the Hex portray a darker mayfly. However, the species description at BugGuide.Net states that the Hex's subimago is pale golden yellow, so we have a subimago. In entomological terms, an imago is the final stage an insect attains during its metamorphosis, so it's the adult form. Our subimago, then, displays the next-to-last stage of our mayfly's metamorphosis.

This points to an interesting feature of mayfly life history, which is that mayflies are unique among insects in that they moult one more time after their wings have fully developed. The next-to-las stage of metamorphosis, or instar -- our yellow subimago -- normally lasts only a few hours. This might explain why ours didn't want to move; it was undergoing many changes that moving might have disrupted, preventing it to undergo its last change, into an adult.

Fly fishermen, who seem to be more knowledgeable about mayflies than anyone else, call mayfly subimagos "duns," and pay special attention to them because at this stage mayflies are the favorite food of many fish, and many fishing flies are modeled after them.

Hex mayfly subimagos are among the most revered "duns" of fly fishermen. On the Hex page of TroutNut.Com, the writer describes that season of year when the Hex's big, yellow subimago emerges en masse, forming clouds of themselves that show up on radar:

"Anglers who only fly fish once a year drive hundreds of miles to play their part in the drama, while the mayflies themselves make the television news by showing up on doppler radar or calling snowplows out of dormancy to remove layers of Hexagenia duns from the bridges."

If you want to see how excited a fisherman can get over a single mayfly species, check out http://www.troutnut.com/hatch/32/mayfly-hexagenia-limbata-hex.

*****

CABBAGEWORM
My Collard plants bolted several weeks ago but I'm letting them flower and fruit, to collect seeds for later plantings. Colorful but smallish caterpillars, reaching only about 3/4-inch (17mm) have appeared chomping on the leaves, as shown at http://www.backyardnature.net/n/14/140517cr.jpg.

These are such distinctive larvae that Bea in Ontario quickly identified them as Cross-striped Cabbageworms, EVERGESTIS RIMOSALIS, a species fairly common in the eastern US, especially the warmer states, and Mexico. The picture shows that younger caterpillars are darker than older ones.

Cross-striped Cabbageworm caterpillars feed on various members of the Mustard Family, including wild ones, but usually are noticed on garden cabbage, collard greens and Brussels sprouts. They pass through four skin-shedding phases, or instars, before pupating and eventually metamorphosing into smallish, triangular-shaped, blotchy-gray moths not nearly as eye-catching as the caterpillars.

Unlike many garden pests, this species is thought to be native American. It's been accidentally introduced into Australia and Jamaica.

*****

HOW BEA USES BUGGUIDE.COM
This week it's been easier to find interesting insects not noticed before than to document new plants, so volunteer bug identifier Bea in Ontario has been busier helping us than usual. By the way, over the years Bea has become quite an expert on the moths of Ontario. You might enjoy scanning her amazing moth page, which still is being added to, at http://www.backyardnature.net/n/a/moo/index.htm.

Sometimes Bea gets back to me faster with identifications than I thought would be possible. I mentioned this to her the other day and she let me in on one of her IDing tricks. I'd sent her a picture of a beetle lounging on a flowering head of a Milk Thistle, Silybum marianum, encountered in Cooks Slough Nature Park on Uvalde's south side, so Bea told me how she came up with that insect's ID. The beetle's picture is at http://www.backyardnature.net/n/14/140517bt.jpg.

Here's how Bea identified the beetle:

1) First go to BugGuide's entry page at http://bugguide.net/ Note that on the left side there's a "Clickable Guide" consisting of simple drawings of many kinds of insects. Because of our insect's hard forewings covering soft, pliable wings beneath the hard covering, Bea knew that our unknown insect was a kind of beetle, so she clicked the beetle icon shaped something like a junebug toward the chart's bottom, in the middle.

2) Clicking the beetle takes us to the page for beetles, Order Coleoptera, where there's interesting text about beetles in general, and some pictures of them. At the top of this page, click on the "Browse" tab.

3) The Beetle-order Page's "Browse" tab takes us to a new page showing pictures of beetles in the four beetle "suborders." Bea writes about the approach at this point: "For beetles we have four choices. Scroll through the pictures and find those looking most like your beetle. Sometimes there is more than one group looking like yours, so just check them all. For the one in our picture I chose "Suborder Polyphaga." So click on the Polyphaga link.

4) The Suborder Polyphaga is a big one. Notice that at the top of that page links are provided to four different pages. Each page holds pictures of beetles in various "superfamilies." Once again, just scroll through the pictures on all four pages until you find images more or less matching your unknown. Our image most matches the "Superfamily Elateroidea" profiled on the second page, so click on the "Superfamily Elateroidea" link.

5) On the Superfamily Elateroidea Page, we find links at the top to three pages profiling beetle "families." Browsing through all three pages, on the last page, "Family Cantharidae," the Soldier Beetles, is chosen. Click that.

6) On the Family Cantharidae Page, several "subfamilies" are profiled. "Subfamily Chauliognathinae" is chosen and that link in clicked.

7) On the Subfamily Chauliognathinae Page, the genus Chauliognathus is chosen, so click on that.

8) On the Genus Chauliognathus Page we find four pages of soldier beetle species illustrated. Bea writes: "Here there's a few that look like yours, for example the first one Chauliognathus basalis - Colorado Soldier Beetle -- click on that one. From here you click on "Info," which gives you any information that Bugguide.net knows about that species, host plants, habitat, size, range. It says they are in Texas. Now click on the "Data" tab that shows a distribution map, and we see they don't seem to be common in Texas. Searching on we come to Chauliognathus omissus, also looking like yours but the map with the "Data" tab doesn't show them in Texas. And so on until we come to: Species Chauliognathus scutellaris. And BINGO!! There's lots in southwestern Texas, and I'm pretty sure we have a match!"

Using the BugGuide procedure, or any picture-matching process, often we're lucky just to attain the genus, or even family. When you get as far as you can go, consider using the image search feature of a web browser, employing as the keyword the lowest-level name you're sure of, in our case the genus name "Chauliognathus." You might even add another keyword in the search window designating your geographical area. For instance, there appears to be only one Uvalde in the world, so when I search on "Chauliognathus Uvalde" I find identified pictures taken of soldier beetles in the Uvalde area by other naturalists, often posted on Facebook. Also I might search on "Chauliognathus Texas."

To confirm your ID or for further help, if you have a good close-up picture you can submit it to BugGuide for help, clicking on the "ID Request" tab atop every BugGuide page.

*****

DWARF PRAIRIE-CLOVER
At the asphalt's very edge a small splash of yellow caught my eye, so I turned the bike back and took a look. It was an especially small wildflower, hardly more than three inches tall (8cm), shown at http://www.backyardnature.net/n/14/140517da.jpg.

Seeing the pinnately compound leaves arising one per stem node, my first impression was that this was member of the big Bean Family, but where those Bean Family flowers? Down on hands and knees, the blossoms looked like they could belong to that family but, if they did, they certainly were unusual with their lower petal so slender and jutting forward so stiffly, and the side petals also jutting out to the sides. A flowering head is seen at http://www.backyardnature.net/n/14/140517db.jpg.

A closer look at the compound leaves found them heavily mantled with long, slender, straight hairs bending close to the leaflets' surfaces, just like we've seen on several Bean Family species, such as some lupines. A compound leaf with sand splattered on it after a recent shower is shown at http://www.backyardnature.net/n/14/140517dc.jpg.

So, yes, this was a member of the Bean Family, the Fabaceae, and with such distinctive features it didn't take long to figure out that this was some kind of prairie-clover, of the genus Dalea. And Dalea isn't to be confused with "Dahlia," the pretty garden member of the Composite Family.

The Bean Family genus Dalea is a big one, with 100-150 known species. Its species mainly occur in Mexico, and are especially adapted for arid habitats. Therefore, in the US east of the Mississippi river the genus isn't well represented, with only three or four prairie-clover species spottily occurring. However, here we have several, so the challenge was to figure out which Dalea we'd found along the road.

Here are the main field marks of our little prairie-clover:

That last matter of it occurring on limestone is especially important because two very small, yellow-flowered, prairie-clover species occur in our area: Dalea nana and Dalea rubescens. Earlier, and sometimes even now, Dalea rubescens was considered a variety of Dalea nana and both can be called Dwarf Prairie-clover. Billy Turner's 2011 paper "Systematic Study of the Dalea nana Complex" states that Dalea nana inhabits mostly non-calcareous or sandy substrates, while Dalea rubescens lives on calcareous, "non-arenaceous" soils. Limestone is very calcareous; "non-arenaceous" means non-sandy.

Since our plants were on limestone and its flower bracts seem to be of the right shape, our plant appears to be DALEA RUBESCENS, which occurs mostly in arid northeastern Mexico, but extends into the US in Arizona, southern New Mexico, and here in southwestern Texas. In the scrubby southern half of Uvalde County, on the Coastal Plain, I bet they have Dalea nana.

*****

PENNYROYAL VARIATION #2
Back East one of my favorite wildflowers was the American Pennyroyal, Hedeoma pulegioides, a member of the Mint Family. The wonderful thing about it was the intensely sweet, minty odor produced when its herbage was crushed. Last year about this time we found a different pennyroyal species here in southwestern Texas, the Slender False Pennyroyal, Hedeoma acinoides. You can review that pretty plant at http://www.backyardnature.net/n/h/hedeoma.htm.

At first, that's what I thought I'd found again this week in a similarly very rocky spot, shown at http://www.backyardnature.net/n/14/140517hd.jpg.

However, it didn't seem exactly the same. The leaves on this week's plant were more slender and the flower paler. A close-up of a flower is at http://www.backyardnature.net/n/14/140517he.jpg.

The Slender False Pennyroyal's upper corolla lobe was longer and abruptly bent upward, but this corolla's upper lobe is short and straight. A close-up of the plant's very hirsute parts is shown at http://www.backyardnature.net/n/14/140517hf.jpg.

So, this is another pennyroyal species, the Drummond's False Pennyroyal, HEDEOMA DRUMMONDII, commonly occurring on well-drained limestone all through the western US except in the Pacific states, and deep into arid northern Mexico.

Drummond's False Pennyroyal smells very good, but I don't think it's as delightful as the American Pennyroyal. Still, traditionally it's been a favorite for teas. Indigenous Americans used it medicinally for ailments ranging from fever, colds and headaches to constipation, menstruation problems and poor appetite. In fact, laboratory studies have found that extracts from the plant produce powerful antioxidant effects and antimicrobial activity.

*****

MARJORAM FLOWERING
Last winter my friend Deborah gave me a potted, woody-based sprout of Marjoram she'd cut from one of her own shrubby plants. I was tickled to have it because I've always heard of Marjoram and I've seen it sold as an herbal spice but I had no experience with it. I didn't know what to expect of the flowers, other than that they'd follow the rules of the Mint Family to which Marjoram belongs, which meant that the corollas probably would display bilateral symmetry like a snapdragon flower instead of radial like an iris. Also it'd bear four or two stamens instead of the more usual five, and the ovary would be deeply four-lobed. You can see my potted plant happily soaking up the sun at http://www.backyardnature.net/n/14/140517th.jpg.

As expected of the Mint Family, the plant bears two leaves per node -- they're opposite -- and the stems are square in cross section. The flowers with their four stamens are not spectacular, but they're clustered in a novel way, as shown at http://www.backyardnature.net/n/14/140517ti.jpg.

In that photo, the fuzzy, green, more or less spherical object in the picture's center, composed of several hairy, disklike objects, is a tightly grouped cluster of flattish calyxes, a calyx being the usually green, cuplike structure beneath a corolla. These flat calyxes are strange, because usually they're bowl-like, and their systematic arrangement in such a cluster is unusual. The calyxes in their cluster take turns flowering, so a cluster might contain calyxes from which corollas have not yet emerged, some from which corollas are emerging now, and some from which corollas already have emerged, so that now the deeply lobed ovaries are maturing into nutlets inside the calyx. Once you pay attention to this very novel construction, you'll never confuse Marjoram with another flowering plant.

Also the above picture shows that Marjoram's white corollas are not as strikingly bilaterally symmetrical as many in the Mint Family. Still, if you look closely at the blossom at the picture's lower, right corner, you'll see that two petals are considerably wider than the other two, so the corolla really is bilaterally symmetrical. You can see the pretty but ordinary looking Marjoram leaf at http://www.backyardnature.net/n/14/140517tj.jpg.

Marjoram is ORIGANUM MAJORANA, though in my old books it's placed in its own genus, Majorana. From the new genus name, Origanum, you might guess correctly that Marjoram is closely related to Oregano. Marjoram originally is from the Mediterranean area and Turkey.

Despite my plant's woody base, in most temperate lands it's grown as an annual that's unable to endure freezes, and doesn't overwinter well inside houses. Even here in southwestern Texas it doesn't survive our mild winters.

Marjoram is described as a good seasoning for soups, stews, dressings and sauce, its leaves tasting milder and with a more delicate flavor than those of Oregano. To produce your own leaves for seasoning, it's advised to pick the leaves just after flower buds appear but before they open, removing no more than a third of the plant's leaves in a single harvest. Once the leaves have been hung up and dried, strip them from the stem.

I didn't do this because I'd rather have the healthy plant than season a soup with its leaves.

*****

FEATURED ESSAYS FROM THE PAST:

"Chopped Onions & Hot-Sauce" from the January 15, 2012 Newsletter, at http://www.backyardnature.net/n/p/120115.htm

"Dandelion Salad & Poke" from the May 4, 2006 Newsletter, at http://www.backyardnature.net/n/p/060504.htm

*****

Best wishes to all Newsletter readers,

Jim

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