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Friday, October 1, 2021

Madrone Mysteries


Texas Madrone

A striking small tree, to 30 feet, the Texas Madrone (Arbutus xalapensis) occurs in protected canyons and mountain slopes of Big Bend, but its range extends eastward to the Edwards Plateau in Travis County.  It is a rare native tree, but can be locally common in the right habitat, preferring grasslands and open oak-juniper woodlands on rocky limestone slopes. Its simple, pointed oval, leathery leaves, 2 to 5 inches long, are evergreen and medium green on top and lighter beneath.  In spring, clusters of small, fragrant, bell-shaped white flowers appear above the leaves, developing into bright red-orange fruits in late fall.  These fruits are relished by many species of birds and mammals and are reported to be edible by humans.

Texas Madrone flower cluster

One of the first mysteries of the Texas Madrone is its bark.  Bone-white and smooth when young, with age it becomes scaly and turns to shades of pink, red, and brown. This older bark peels away in patches and strips, revealing a smooth reddish bark underneath, and gives the tree some of its more colorful, old colloquial names such as Lady’s Leg and Naked Indian. But why does the bark exfoliate?  The most commonly accepted theory is that it is an evolutionary development to rid the tree of lichens and parasites such as wood boring insects, preventing their buildup and reducing the chance of disease.

Peeling Texas Madrone bark

Ashe Juniper nurse tree
protecting a young Texas Madrone

While it is one of the most interesting and beautiful native trees of Texas, another mystery of the Texas Madrone is that it is extremely temperamental to grow.  Its propagation requirements are complex, and it is very difficult to successfully transplant from the wild.  Madrones have a fine root system that is easily damaged, and even slight root damage is usually fatal to the tree.  Additionally, new seedlings require the protection of a ‘nurse tree’ to become established.  A nurse tree is a larger, faster-growing tree that safeguards the seedling while it gets established by providing shade, shelter from the wind, and protection from grazing animals.  For the Texas Madrone, its nurse tree is most often the native Ashe Juniper (Juniperus asheii). Adding to its temperamental nature, this tree is slow-growing, taking more than a century to attain a fully mature height.

Texas Madrone fruit

Texas Madrone trees flower from late February to early March, while their fruits don’t mature until late November to late February.  Like several species in the genus Arbutus, the fruits begin to form in mid-spring but fruit development is delayed for several months so that the next spring’s new flowers begin to appear while the previous year’s fruits are ripening.  This timing delay results in a short period of time when both fruit and flower can be simultaneously present on a tree, yet another intriguing characteristic of the mysterious Texas Madrone!

Saturday, August 28, 2021

Hoppin' Orthoptera

Grasshopper nymphs are often mini versions of the adults

Take a walk through a meadow on a late summer or early fall day, and you’ll no doubt encounter members of the insect order Orthoptera: grasshoppers, crickets, and katydids.  While their Greek name translates to ‘straight wings’, these insects are better known for their jumping ability and powerful hind legs that can propel them to 20 times their body length. 

Abundant, large, colorful, and often noisy, orthopterans are unlike other insects in that they undergo an incomplete or gradual metamorphosis.  Their simple lifecycle consists of an egg, nymph, and adult, where the nymphs look similar to adults, but lack completely developed wings.  Eggs typically hatch in the spring, nymphs develop through the summer, adults mate and reproduce in late summer and fall, with winter passing in the egg stage.  They have three basic body parts: the head, which contains sensory parts such as antennae, eyes, and mouthparts; the thorax, which contains the legs and wings required for movement; and the abdomen, which bears the digestive and reproductive organs.

The use of sound is crucial in courtship, with each species having its own distinct song.  Males attract mates through stridulation, or producing sounds by rubbing the upper and lower wings or the hind leg and wing together creating a vibration that is species-specific.  The auditory organs for orthopterans are not located on their heads, however, but on the abdomen for grasshoppers and the front legs of crickets and katydids.

Differential Grasshopper

Common throughout Texas is the Differential Grasshopper (Melanoplus differentialis), which is brown to olive-green and yellow and up to 1.8 inches long, with black herringbone markings on its legs.  It feeds on both grasses and broadleaf plants, although it prefers the latter, and is often found in areas of lush vegetation. Both nymphs and adults tend to aggregate together, and the adults are found from July to October.

Obscure Bird Grasshopper

Also found thoughout Texas is the Obscure Bird Grasshopper (Schistocerca obscura).  This large grasshopper, to 2.5 inches long, has olive-green forewings and typically a pale yellow-green dorsal stripe from the front of the head to the wing tips. While females can lack this stripe, both sexes have blackish-purple tibia with yellow, black-tipped spines.  This species prefers fields and open woodlands, and can sometimes feed on flowers and shrubs.

Green-striped Grasshopper

The Green-striped Grasshopper (Chortophaga viridifasciata) is found everywhere in Texas except for the southernmost portion of the Trans-Pecos.  Up to 1.5 inches long, it has both a green form (usually females) and a brown form (usually males). Between forms, the main difference is the coloring of the head, thorax, and outer face of the hind femora, with the abdomen always being reddish-brown. This grasshopper prefers wet areas with short grasses on which to feed.    

Narrow-winged Tree Cricket

More often heard than seen, Tree crickets (Oecanthus sp.) are whitish to light green, with long antennae and slender bodies.  In late summer from dusk into the evening hours, the males begin to chirp, with the rate of the chirp correlating to the outside temperature.  If you count how many chirps you hear in 15 seconds and add that to 40, you’ll come surprisingly close to the actual air temperature in degrees Fahrenheit.  

Field Cricket

Field crickets (Gryllus sp.) are dark brown to black, about 1 inch long, live in cool, dark areas, and normally emit high-pitched, continuous calls.  Those that live in caves are dark brown, have well-developed hind legs, and exhibit a hunchbacked appearance.

Fork-tailed Bush Katydid

The antennae of katydids are hair-like and at least as long as the body, superbly represented by the Fork-tailed Bush Katydid (Scudderia furcata).  This all-green katydid is often found in weedy fields, thickets, forest edges, and along roadsides. Up to 2.2 inches long, the first generation matures in late spring and the second in early fall.  Interestingly, the overall size of the adults varies and is directly related to how fast they must mature in order to fully use the growing season to produce the maximum number of generations.

Often, what you can’t identify by sight during the day becomes clear when it sings, calls, buzzes, or chirps at night.  Immerse yourself in the nighttime soundscape, and hear your way to discovery!

Wednesday, July 28, 2021

Outmaneuvering Mosquitos

Mosquitos can be a nuisance in the hot summer months.

As the temperatures start to increase so do the ads for mosquito-control companies that offer to blanket spray residential landscapes.  While many of these businesses claim that their treatments only kill mosquitos and other pests, in reality the broad-spectrum insecticides they use kill many other species.

Broad-spectrum insecticides are indiscriminate, and along with killing mosquitos, they also kill pollinators and other beneficial insects such as bees, butterflies, moths, caterpillars, dragonflies, damselflies, and lady beetles.  The damage continues further up the food chain, when birds die as their insect food disappears and aquatic animals such as fish die when these chemicals wash off our landscapes and flow into nearby creeks, ponds, rivers, and lakes. Even spraying with essential oils such as peppermint, rosemary, and lemongrass is discouraged, as these can also kill beneficial insects.

Keeping mosquitos at bay can be vital, with many mosquito-borne tropical diseases such as West Nile, Zika, and Dengue fever spreading in range.  However, there are other natural, safer alternatives to using broad-spectrum insecticides.  It starts with understanding that mosquitoes can breed in less than one inch of water, and that the most effective way to reduce their numbers is to target the larvae, not spray adults.  

Moving water discourages female mosquitoes from laying eggs.

Begin by removing any standing water in gutters, bird baths, flower pot saucers, children’s pools, pet bowls, watering cans, and anything else that can hold water. Female mosquitoes avoid laying eggs in moving water, so consider adding a small pump or fountain to a water feature. For standing water that cannot be drained, use a mosquito dunk that contains the natural bacterium Bti (Bacillus thuringiensis israelensis) that kills mosquito larvae as they hatch, and consider adding native mosquitofish (Gambusia species) if the water feature is permanent.  Mosquitos are weak flyers, so even setting up fans reduces their ability to find an individual.

Black-chinned Hummingbirds get protein from eating insects like mosquitoes.
Neon Skimmer dragonflies love to prey on mosquitoes.

Most surprising to many, those who garden for wildlife using native plants have fewer mosquito problems than those with non-native turf lawns.  Native plants attract natural mosquito predators such as birds (warblers, wrens, woodpeckers, hummingbirds), dragonflies, damselflies, frogs, turtles, and bats.  Hummingbirds consume hundreds of insects daily in addition to drinking nectar, dragonflies and turtles eat mosquito larvae before they can hatch, frogs specialized sticky tongues nab all kinds of insects, and bats consume millions of insects on the wing.

The sticky tongues of frogs like this Leopard Frog can catch adult mosquitoes.
Red-eared Slider turtles eat mosquito larvae before they hatch.

It is important to note that even if you have a native landscape and don’t spray for mosquitos but your neighbors do, you will still lose pollinators and other beneficial insects.  Recent studies have shown that nearly 3 billion birds have disappeared from North America since 1970 due to loss of their insect prey, and many insect species are rapidly declining or vanishing altogether. 

Make your voice heard by spreading the message that insecticides are significant contributor to wildlife decline, and how we outmaneuver mosquitos in our landscapes truly matters to us all.

Saturday, July 24, 2021

Beautiful Hindwings

Can you find the underwing moth?

Commonly known as underwings, the genus Catocala is a large group of moths where most species are somberly clad with brown or gray-shaded forewings, often in variable, cryptic patterns of wavy lines closely resembling tree bark.  It is their hindwings, kept hidden at rest, that are typically a vivid orange, red, or yellow, and marked with black bands or stripes. 

The genus Catocala comes from the Greek kato meaning ‘rear or lower one’ and kalos meaning ‘beautiful’, together translating to ‘beautiful hindwings.’ Of the more than 100 underwing species found in the United States, 15 or so are known in Travis County, including the Ilia Underwing (Catocala ilia), Little Nymph Underwing (Catocala micronympha), and Ultronia Underwing (Catocala ultronia).

Ilia Underwing

The Ilia Underwing, also known as the Beloved Underwing or Wife Underwing, is one of our most common large underwings.  It has a total length to 1.8 inches, and gray to brownish forewings with a bold black line above a white or white-outlined spot. The reddish-orange hindwings have two black bands, and a pale orange, checkered fringe.  It utilizes oaks for its host plants, especially red oaks such as Shumard’s Oak and Southern Red Oak.  Its common and scientific name Ilia likely refers to the mythical mother of the twins Romulus and Remus, who were the mythological founders of the city of Rome.

Little Nymph Underwing

One of our smaller underwings with a total length of up to 1 inch, the Little Nymph Underwing has brown to grayish forewings typically marked with a dark, curving, shadow-like crescent.  The golden orange hindwings have two black bands, sometimes broken, and a pale, checked fringe.  It prefers white oaks as host plants, specifically Post Oak, Bur Oak, and Coastal Live Oak.  Its species name comes from the Greek and means ‘little bride or mistress.’

Ultronia Underwing

The Ultronia Underwing is medium-sized underwing to 1.3 inches in length, and is identified by its grayish-brown forewings marked with a darker brown shading on the inner edge.  The reddish hindwings have two black bands and a mostly gray fringe. Escarpment Black Cherry and Coastal Live Oak are its preferred host plants, and its common and scientific names are said to have come from the name of a Greek island.

It is believed that the bright colors of these moths’ hindwings, which usually form roughly concentric patterns, resemble the eyes of a predatory animal when suddenly flashed toward danger. Underwings are also said to possess fairly well-developed hearing organs, allowing them to evade nocturnal predators such as bats.  Their cryptic forewings keep them hidden during the day as they roost on tree bark and in crevices, and even in their larval form their coloring and patterns often mimic gray bark or green lichen.  While most active shortly after nightfall, several species have a second activity period for a few hours around noon, when these beautiful hindwings can sometimes be found on the wing in broad daylight!

Saturday, June 19, 2021

Bodacious Borers

Cottonwood Borer

As spring turns into summer in Central Texas, the heat brings out some of our most interesting creatures, most notably the native wood-boring beetles.  This group encompasses many species and families of beetles, all of whom eat wood either in their larval or adult form.  Most often they are found in or around dead or dying trees, as they are vital players in enabling the turnover of weak trees with strong ones, and acting as primary decomposers of wood which allows for the recycling of nutrients back into the soil.

One large family of beetles in the wood-boring group is the longhorn beetles, or Cerambycidae, typically characterized by their extremely long antennae which are often as long or longer than the beetle’s body.  Their family scientific name comes from the mythological Greek shepherd Cerambus, who was turned into a large beetle with horns after an argument with nymphs.  Three of the more noticeable wood-boring longhorn beetles in our area include the Banded Hickory Borer (Knulliana cincta), Cottonwood Borer (Plectrodera scalator), and Texas Bumelia Borer (Plinthocoelium suaveolens plicatum).

Banded Hickory Borer

With a body length of up to 1.4 inches, the Banded Hickory Borer is a fairly slender, typically gray to reddish-brown beetle with a pair of pale marks near the base of the elytra or wing covers that are sometimes absent, and tiny spines at the ends of the elytra.  Eggs are laid by the adults in bark crevices or directly into hardwoods such as oak, pecan, walnut, willow, and hackberry, upon which their larva feed.  In their first season, the larva feed just beneath the bark, then head deeper into the wood as they develop, a cycle which takes two to three years to complete.

Cottonwood Borer

The Cottonwood Borer is an elongate, unmistakably robust beetle with black and white markings that are formed by contrasting areas of white pubescence or fine short hairs on black body parts.  At a body length of up to 1.6 inches, the summer-active adults lay eggs in August and September on cottonwood and willow, where larva bore into the base and overwinter.  After two or three years to reach maturity, they pupate in chambers beneath the bark and emerge as adults in late spring, and are often found feeding on new shoots, leaf petioles (stems), and the bark of their host trees.

Texas Bumelia Borer

One can hardly miss the bright iridescence of the metallic green Texas Bumelia Borer, with its contrasting reddish-orange and black legs. The larva of this species feed on gum bumelia and mulberry, developing in the roots and trunks of these host plants.  With a body length of 1.5 inches, the adults are diurnal and often found on the trunks of their host plants, although they typically feed on flower nectar and are attracted to lights.

Despite their large size, most native wood-boring beetles are not pests.  Instead, they take advantage of dead and dying trees and aid in the natural decomposition process. As you venture out and about this summer, see if you can find some of these bodacious borers!

Tuesday, May 18, 2021

Beguiling Bloomers

Pink Stonecrop

Springtime in Central Texas brings a host of familiar wildflowers blooming in meadows and woodlands, and along grassy roadsides. But each year the seasonal conditions may vary, based largely on the timing and amount of rainfall.  While many species are widespread from year to year, some appear infrequently, others only in certain habitats, and many go almost completely unnoticed.

Clasping Venus’ Looking-glass

Clasping Venus’ Looking-glass or Clasping Bellflower (Triodanis perfoliata) is a distinctive annual that can be found growing in open often disturbed areas, sometimes appearing even in cultivated flower gardens.  In April and May, violet-blue, 5 petaled, wheel- to bell-shaped flowers, 0.5 to 0.75 inches across, are set singly in the axils of rounded green leaves that clasp the erect, slender, unbranched stems.  Inconspicuous at 6 to 18 inches high, this species is differentiated from five other Triodanis species found in Texas by its almost circular, toothed, clasping leaves.

Pink Stonecrop, also called Widow's Cross

Pink Stonecrop or Limestone Stonecrop (Sedum pulchellum), is a low-growing, apparently rare annual found on rocky ground in full sun, often among cactus and other Sedum species. Smooth, stem-clasping, cylindrical pale to lime green leaves (often with a reddish tinge), to 1 inch long, are densely arranged along the ascending to spreading stems.  These stems are topped with horizontally branched inflorescences that bloom from March to May, with numerous 4-petaled, pale pink flowers, to 0.5 inches across.  The petals are arranged in a cross-like pattern, giving rise to its other common name of Widow’s Cross. The Travis County population of this species, most often found on hilltops in the Bull Creek watershed, is disjunct by over 150 miles from other more eastern and northern populations, and likely represents the southwestern limit of its native distribution.

Heller's Plantain

Highly overlooked but quite common is Heller’s Plantain or Cedar Plantain (Plantago helleri), an erect annual that grows only in Central to West Texas and in southern New Mexico, typically in shallow, stony soils and on limestone bedrock exposures. From March through May, this species displays unusual, slightly overlapping flowers clustered at the top part of each stalk.  The flowers are quite small at 0.25-inches wide, with 4 off-white, nearly translucent petals that have a dark red center.  The stalks, to 10-inches high, arise from narrow, linear, basal leaves, to 8-inches long, and both stalks and leaves are softly hairy.  This species is can be commonly found along gravelly roadsides, and it is one of the host plants for the beautiful Common Buckeye butterfly.

Common Buckeye

Each spring, remember to look beyond the bluebonnets, paintbrushes, firewheels, and Mexican hats and take a closer look, because you just might be rewarded with one of these beguiling little bloomers!

Wednesday, April 14, 2021

Resilient Trees

The beginnings of Winter Storm Uri

With winter storm Uri well behind us, many observations are being made regarding which tree species successfully survived the 8-day stretch of extreme winter weather conditions.  First and foremost, all trees that are native to Central Texas generally fared much better than their non-native counterparts.  Over the centuries, native species have adapted to all sorts of weather conditions, from cycles of droughts and floods, heat and cold, and even accumulations of ice or snow.  These adaptations greatly increase each native species’ resiliency over time.

A second factor that determined the survival of a native tree species was whether it was evergreen or deciduous.  The foliage of evergreen species increases the surface area that can trap ice and heavy snow, causing limbs to bow, split, and break, which can weaken the entire structure of the tree.  While deciduous trees can be covered in ice and snow, in winter they do not have foliage that can trap the extra weight that can cause permanent damage.

Third, established plants have a much better chance of survival in extreme winter weather conditions, so now is the time to plant!   While there are many desirable native trees that are deciduous, there are several that are also attractive bloomers in the spring, including Escarpment Black Cherry (Prunus serotina var. eximia), Roughleaf Dogwood (Cornus drummondii), and Rusty Blackhaw Viburnum (Viburnum rufidulum).

Escarpment Black Cherry in bloom

Escarpment Black Cherry fruit

Found only in the limestone-based soils in Central Texas, Escarpment Black Cherry is a distinct and isolated subspecies of native Black Cherry (Prunus serotina). Growing up to 50 feet tall, it is distinguished from other subspecies in Texas by its intermediate height and its virtually hairless, pointed elliptical green leaves with finely toothed margins that turn golden yellow in fall. It has attractive silvery bark and long showy clusters of tiny white flowers in March to April followed by purplish-red fruits that are favored by wildlife.  This native cherry prefers sunny areas in wooded canyons and on slopes, and is a larval host plant for many species of butterflies and moths including Eastern Tiger Swallowtail, Two-tailed Swallowtail, Cecropia Moth, and White Furcula.

Roughleaf Dogwood in bloom

Roughleaf Dogwood fruit

Roughleaf Dogwood is a small tree to 16 feet with opposite, prominently veined, oval, green leaves with an abruptly drawn-out tip, slightly rough above and slightly velvety below, that turn purplish-red in fall.  From April to early June numerous broad clusters of cream-colored flowers appear at the ends of branches, developing into small, fleshy, bright white, spherical fruits.  This native dogwood prefers partially shady, wooded limestone hills, and provides cover for various species of wildlife, especially birds, as it spreads from root sprouts and if allowed, eventually creates a natural thicket.

Rusty Blackhaw Viburnum in bloom

A shapely small tree, typically to 18 feet but sometimes taller, Rusty Blackhaw Viburnum has attractive, glossy dark-green paired leaves that turn reddish-purple in fall, reddish-brown twigs, and dark bark that separates into rectangular plates. Platter-shaped clusters of tiny, creamy white flowers in March to April are followed by small, oval, waxy, blue-black fruits that are relished by several species of birds and mammals.  This native viburnum prefers woodland edges and thickets in partial shade, and is of special value to native pollinators like bumble bees.

Rusty Blackhaw Viburnum fruit

Rusty Blackhaw Viburnum fall color

It’s important to note that while winter storm Uri was no doubt an exceptional weather event, it’s never too early to plant some of our more resilient native trees!