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Thursday, October 3, 2019

Night Bloomers

Berlandier's Trumpets
Many night blooming flowers have white or light-colored blossoms, a strong fragrance (although not always to human noses), and open by night and close by day.  These flowers are extremely important nectar sources for pollinators, and they are attracted to these flowers’ nectar mainly by scent.  Two of our best night blooming native plants are Berlandier’s Trumpets (Acleisanthes obtusa) and Jimsonweed (Datura wrightii).

Closeup of Berlandier's Trumpets
Also known as Vine Four O’Clock, Berlandier’s Trumpets is an upright perennial herb or climbing vine up to 6 feet long, easily controlled but often clambering over shrubs and small trees if left unchecked.  Its opposite, bright green leaves are triangular shaped, about 1.5 inches long, with slightly wavy edges.  But it is its white to light pink trumpet-shaped flowers, about 2 inches long, that bloom from April to December, producing a fragrant scent when open at night.  Berlandier’s Trumpet does well in full sun to part shade, is drought tolerant, and easy to grow and maintain.

Jimsonweed is a 3 to 6 foot tall stoutly branched herb, with alternate, coarse, large gray-green leaves that are broad at the base and pointed at the tip.  While its foliage is often described as rank-smelling, its flowers are sweetly fragrant white trumpets, up to 8 inches long, sometimes tinged with purple at the edges.  It blooms from May to November, and its flowers open in evening and close during the heat of the day.  

Jimsonweed Bloom

The fruit of this plant is a very distinctive spiny, globular capsule up to 1.5 inches in diameter, which opens fully when ripe.  Jimsonweed has several other common names such as Sacred Thorn-apple, Angel Trumpet, Devil’s Trumpet, and Sacred Datura. Some of these names refer to its use as a hallucinogen in Native American ceremonies, but it is important to note that all parts of this plant are toxic to humans.

Jimsonweed Fruit
Both of these native night blooming species attract several species of Sphinx moths (sometimes known as hawkmoths or hummingbird moths) as well as other pollinating insects such as long-tongued bees, butterflies, and hummingbirds.  But it is the Jimsonweed that has mastered the art of mutualism, with its partner the Carolina Sphinx.  

Carolina Sphinx
While it is common for this plant to benefit from its relationship with the Carolina Sphinx (Manduca sexta) in the form of pollination, in turn it provides nectar for the adult moth and is the host plant for the moth’s caterpillars.  These large caterpillars (known to gardeners as ‘tomato hornworms’), consume many or all of the Jimsonweed’s leaves. But the plant is prepared for the attack, storing resources in its massive root enabling it to produce more leaves for the next generation of caterpillars.  In effect, Jimsonweed grows its own pollinators to ensure its reproductive success!

Thursday, September 5, 2019

Aquatic Apalones

Spiny Softshell Turtle
The genus Apalone is thought to come from the Greek apo meaning ‘separate’ and the Anglo-Saxon alone meaning ‘solitary’, as well as the  Greek apalos meaning ‘soft’ or ‘tender.’  All of these terms apply to the members of this genus, which is comprised of the softshell turtles native to North America.  Turtles of this genus exhibit marked sexual dimorphism, or the condition where the two sexes of the same species exhibit different characteristics beyond their sexual organs.

Females grow to twice the size of males, in terms of carapace or shell length.  In males, the claws on their front feet are longer than those on the back feet, enabling them to better hold on to the female while mating.  In females, the claws on the back are longer, for digging into sandbanks in order to lay her eggs.  Lastly, males have a thicker, stout tail that extends well beyond the edge of its carapace, but the female’s tail is relatively thin and barely extends beyond the carapace.  From a behavioral standpoint, the female is much more solitary, wanders more, and requires deeper water, while the male often congregates with juveniles in sandy shallows and while basking along exposed banks.

Spiny Softshell Turtle
There are two species of softshell turtle in Texas. The more common Spiny Softshell Turtle (Apalone spinifera) is found throughout the state, while the Smooth Softshell Turtle (Apalone mutica) is found only in parts of the eastern two-thirds of the state. The Spiny Softshell’s olive-gray or tan carapace is leathery and flat, and has small spines along the front edge, which explains its species name.  At home in rivers, lakes, ponds, and other bodies of water with muddy or soft bottoms, its spends its time feeding on aquatic insects, fish, and crayfish, basking or floating at the surface, or buried in soft, shallow substrates.  Its long neck and snorkel-like nose allows the turtle to breathe at the water’s surface without having to leave its buried location. Females typically grow to 22 inches, while males top out at 8.5 inches in length.

Smooth Softshell Turtle
The Smooth Softshell’s olive-gray to brown carapace is also leathery and flat, but lacks any spines, bumps, or projections.  This characteristic is reflected in its species name, which means ‘shortened’ or ‘docked.’  It also prefers bodies of water with soft, sandy bottoms, and basks on banks, logs, rocks, or under shallow water with its long nose exposed.  Primarily insectivorous, it will also consume vegetation and small invertebrates and fish.  Smaller than the Spiny Softshell, females grow to 14 inches and males to 7 inches in length.

One odd but amazing fact about softshell turtles is that they are believed to absorb 70% of their oxygen through their skin.  The other 30% comes from pumping water in and out of their pharynx or throats, which contain many tiny projections of tissue with small blood vessels that provide a huge surface area for oxygen absorption.  This adaptation allows them to remain underwater for several hours.  Now that’s one highly aquatic Apalone!

Tuesday, August 6, 2019

A Different Kind of Longhorn

Cottonwood Borer

The Cerambycidae are a family of longhorn beetles, typically characterized by extremely long antennae, often as long as or longer than the beetle’s body.  Also called longicorns, over 400 species have been described in Texas alone.  The scientific name of this beetle family is named after the shepherd Cerambus, a mythical Greek figure who was transformed into a large beetle with horns after an argument with nymphs.  Most of these beetles can fly well and are found on tree trunks, logs, flowers, or come to lights at night.  Some even squeak as a defense mechanism when held, making a rocking motion with their head which rubs tiny ridges against the inside surface of their thorax.

Cottonwood Borer
Two of our more common longhorn beetles are the Cottonwood Borer (Plectrodera scalator) and the Long-jawed or Horse-bean Longhorn Beetle (Trachyderes mandibularis).  The Cottonwood Borer is one of the largest insects in North America, reaching 1.6 inches in length and 0.5 inches in width.  It has a bold black and white pattern on its body with long black antennae.  The white portions of the pattern are actually microscopic masses of hair.  Adults are active by day, feeding on leaf stems and shoots of cottonwood trees.  The female bores small holes in the base of the tree to lay her eggs.  The larvae take up to 2 years to mature, then they pupate for about 3 weeks in a root below ground, and once metamorphosis is completed they chew their way out of the root and dig their way to the surface.

Long-jawed Longhorn Beetle
Long-jawed Longhorn Beetle has a glossy black or dark brown body with 4 generally large but sometimes reduced yellow to yellow-orange markings, and segments of its antennae and legs alternating between black and yellow-orange.  It can grow to a length of 1.3 inches, and is generally common from March to November.  Its species name comes from the fact that the males have much expanded jaws or mandibles. Active during the day, adults are mostly found near wounded trees as they feed on oozing sap, and its larvae feed on native hackberries as well as non-native ficus and tamarisk species.

Goes fisheri
One of the subfamilies of the Long-horned Beetles is the Lamiinae, or Flat-faced Longhorns.  This includes the 9 New World species in the Goes genus, one of which is rare and endemic to Central Texas.  This species, Goes fisheri, was first described in 1941, but does not have a common name.  Beetles in this genus are typically twig girdlers or stem borers, although the food plant of G. fisheri is currently unknown.  It is distinguished from a more common species, G. pulcher, or the Hickory Borer, by the grayish pubescence of its elytra or wing covers.  G. fisheri is just over 1 inch long, not including its antenna, appears to be nocturnal in its habits, and is attracted to artificial light. 

This large family of longhorns includes beetles called sawyers, pruners, and girdlers in addition to borers.  Most are found in dead or dying wood, and some mine live plants.  While many of these beetles are considered to be occasional pests, it should be noted that they literally help shape the forest canopy and assist in recycling dead wood into precious soil.  All the more reason to appreciate this different kind of longhorn!

Saturday, June 29, 2019

Some Like It Hot

Eastern Ringtails, a type of Clubtail, obelisking.
The dog days of summer are upon us, and a long stretch of sultry weather lies ahead.  It can be a challenging time for people and for wildlife, but for some, it is their chance to put on a show. 

Bouquets of Mountain Pinks
Mountain Pink close up
Mountain Pink (Zeltnera beyrichii), also called Meadow Pink, Catchfly, or Quinineweed, is an annual herb less than a foot tall and best described as a neat bouquet of small, pink flowers.  Blooming May through July, Mountain Pink sprouts up like an inverted cone 8 to 12 inches high, on hot, rocky hillsides, limestone outcrops, and along gravelly roadways.  Its leaves are threadlike and are held below the multiple 0.5 to 1.0 inch wide showy pink five-petaled blooms that provide nectar for moths, butterflies, bees, and other insects.

Woolly Ironweed
Woolly Ironweed (Vernonia lindheimeri) is a 10 to 30 inch high clumping perennial, with woolly gray stems and long, narrow leaves.  Its bright purple flowers lack true petals, but the disk flowers are arranged in showy, terminal clusters.  A well-behaved species that should be used more often in gardens and landscapes, Woolly Ironweed blooms from June to September, and prefers open hillsides, roadsides, and fields offering full sun.  It is a good nectar source for many species of butterflies during the heat of summer, and is highly deer-resistant.

Blue Dasher, a type of Skimmer, obelisking
To prevent overheating on hot, summer days, some dragonflies and damselflies assume a handstand-like position called ‘obelisking.’  They raise their abdomens until the tip points up toward the sun, which helps to minimize the surface area of their body that is exposed to solar radiation.  Both males and females of these species will raise their abdomens when the temperature is high, and lower them again if shaded. Laboratory experiments have shown that this behavior is effective in stopping or slowing the rise in their body temperature.  This method of thermoregulation is practiced by about 30 different species in the Skimmer, Clubtail, and Broadwing Damsel families.  All are considered ‘perchers’ or sit-and-wait predators that spend a considerable amount of time stationary.

A sure sign that we are in the midst of a hot summer is the sound of cicadas buzzing in the air.  For their size, cicadas make as much noise as a large animal, and can be heard up to a quarter of a mile away.  In fact, the word ‘cicada’ is a direct derivation from the Latin meaning ‘buzzer.’  Many common species of cicadas in North America are in the genus Megatibicen  and are generally called the annual or ‘dog-day’ cicadas because they emerge every year in July and August, the dog days of summer.

Resh Cicada, Megatibicen resh
Male cicadas have structures called ‘timbals’ on the sides of their abdomens, and it is with these structures that they create their buzzy songs.  Unlike grasshoppers or crickets that rub their wings or legs together to produce sound, cicadas vibrate these timbals against their hollow abdomens, which amplifies the resonance of the sounds. They can even modulate the sounds by wiggling their abdomens toward or away from the tree trunk on which they are perched.  Each species has its own distinctive sound, and they use different mating songs to attract the appropriate mate.

Even in the heat of a long Texas summer, nature is busy going about its mysterious ways, offering sights and sounds that can recalibrate our senses, and allow us to continue to appreciate all that it has to offer.

Monday, June 3, 2019

Mariposa de la Muerte

Commonly known as owlet moths, cutworms, or armyworms, moths in the Noctuidae family make up one of the largest families of Lepidoptera.  The word Noctuidae is derived from the Latin word noctua meaning ‘little owl’ and the largest moth in this family in the continental United States is the Black Witch (Ascalapha odorata).

The Black Witch moth has been known as mariposa de la muerte or ‘butterfly of death’ since the time of the Aztecs, when it was believed that they were harbingers of death.  With a wingspan of up to 6 inches, its upperside is mottled dark brown to grayish-brown with hints of iridescent purple and pink, and females, which are slightly larger and lighter in color than males, have a pale almost lavender-pink median band through both fore and hind wings.  

A Black Witch (male) attracted to our mercury vapor light
Common to abundant in the New World topics as far south as Brazil, the Black Witch flies year-round in south Florida and the Rio Grande Valley of Texas.  In June and July, summer monsoons in Mexico trigger this fabulous creature to migrate north through Texas, where it is often found roosting in garages, under eaves, or under bridges.  It has the ability to migrate great distances over bodies of open water, such as the Gulf of Mexico, and one specimen was recorded in 1903 in Leadville, Colorado, caught in a snowstorm on the Fourth of July!

Primarily nocturnal, the adult Black Witch is attracted to light and fermenting fruit.  Its larvae feed at night on a variety of cassias, acacias, ebony, mesquite, and other woody legumes, and rest during the day hidden under bark and branches.  Up to 3 inches long, its caterpillar is dark gray tinged with brown, with a pale stripe down the back and dark stripes down the sides, and it relies on this natural camouflage to make it difficult to spot.  Pupation occurs on the ground in scattered leaf litter within a fragile cocoon.  Black Witches breed year round in overlapping generations, and their adult stage is thought to last only three or four weeks.

A Black Witch (female) perched above our front door!
At first glance, this very large moth is often mistaken for a small bat hovering around a porch light, but it will eventually land and linger for several hours if undisturbed.  If this happens to you, you can only hope that the South Texas legend of the Black Witch is true, as it states, “If a Black Witch lands above your door and stays there for a while, you could win the lottery!”

Sunday, May 19, 2019

Poisonous or Venomous?

Poison Ivy
Often used interchangeably when describing some plants and animals, in reality poisonous and venomous mean two different things.  Poisonous describes plants or animals that are harmful when consumed or touched.  Venomous refers to animals that inject venom into their prey, by means of a bite or sting, when hunting or for self-defense.  To add to the confusion, all venoms are a poison but not all poisons are venoms!

Poisonous species typically produce a toxin that can range from irritant to fatal. Plants such as Poison Ivy (Toxicodendron radicans) and some members of the Spurge family are considered irritants when they come in contact with skin, but this effect is produced through different mechanisms.  Nearly all parts of the Poison Ivy plant contain urushiol, which is a substance that gives us contact dermatitis, or a severely itchy and painful inflammation of the skin.  

Texas Bull Nettle
Spurges such as Texas Bull Nettle (Cnidoscolus texanus) and Betonyleaf Noseburn (Tragia betonicifolia) have raised structures called trichomes that are capable of ’stinging' animals and humans that brush against them.  These plants have trichomes on their leaves and stems that have bulbous tips that break off and reveal needle-like tubes that pierce the skin. They can cause an itching, burning rash by emitting onto the skin a mix of acetylcholine, formic acid, histamine, and serotonin.  

Jimsonweed or Sacred Datura
One local native plant, Jimsonweed or Sacred Datura (Datura wrightii) goes well beyond irritant to hallucinogenic and even fatal if ingested.  All parts of this plant contain toxic alkaloids, and the narcotic properties of this plant have been known by humans since before recorded history.  They once figured prominently in important religious ceremonies of various southwestern Native American tribes.

Gulf Coast Toad
Animals that are poisonous include most amphibians (frogs, toads, salamanders, and newts), that have some amount of toxins on their skin and within other tissues. Special skin glands produce useful proteins, some for use in respiration, others for fighting bacterial or fungal infections, and at least one in each species that is used for defense.  For example, many toad species will release their toxins when they feel threatened, such as when they are caught by a dog or cat, and can trigger drooling, vomiting, and respiratory or cardiac problems.

Western Diamondback Rattlesnake
While some snakes are the most commonly known venomous animals, all spiders, some lizards, and many bees, ants and wasps are venomous as well.  The venoms they inject through a bite or sting contain various classes of toxins designed to perform specific biological effects such necrosis or death in multiple cells (necrotoxins) or individual cells (cytotoxins), disruption of the nervous system (neurotoxins), or damage to muscle tissue (myotoxins).   The venom of our Western Diamondback Rattlesnake (Crotalus atrox) carries both necrotoxins and myotoxins, Black Widow spiders (Latrodectus macrons) carry both neurotoxins and cytotoxins, and Striped Bark Scorpions (Centruroides vittatus) and Texas Redheaded Centipedes (Scolopendra heros) carry neurotoxins.

Striped Bark Scorpion
Texas Redheaded Centipede
While the vast majority of snake toxins are transferred by bite, one exception includes garter snakes (Thamnophis sp.), which are small and harmless in terms of their bite but are toxic to eat because their bodies absorb and store the toxins of their amphibious prey.  In our area, these snakes include the Black-necked Garter Snake (T. cyrtopsis) and the Western Ribbon Snake (T. proximus).

Western Ribbon Snake
It is important to keep in mind that many plants and animals that are poisonous or venomous are not necessarily a guaranteed threat to humans, as much depends on how the plant or animal is encountered, its toxicity level, and the amount of toxin absorbed.  Regardless, respecting these species and giving them their space is the cardinal rule.  Interestingly, the medicinal use of venoms for therapeutic benefit in treating diseases dates back to 380 B.C. in ancient Greece.  Today, the venoms produced by different organisms, which contain hundreds of different bioactive elements, are isolated, purified, and screened, then studied to identify components that may have desirable therapeutic properties.  This research is often the starting point for developing a therapeutic drug, and those types of drugs on the market today are used to lower high blood pressure, relieve severe pain, act as blood thinners, treat Type 2 diabetes, and stop bleeding during surgical procedures.

Sunday, April 7, 2019

Royal Ruse

As spring unfolds in Central Texas, butterflies begin to appear ever present in our gardens and landscapes.  A subfamily of the Brushfoot butterflies, milkweed butterflies are a group of butterflies whose larva feed only on various milkweed species, and these plants provide the adults with certain chemicals that make them naturally distasteful to most predators.  This subfamily is composed of ‘the royals’, better known as the Monarch (Danaus plexippus), Queen (Danaus gilippus), and Soldier (Danaus eresimus).

Monarch ventral, or underside.
The well-known Monarch is probably the most famous butterfly in North America, but it often confused with the Queen and Soldier.  Monarchs have rich cinnamon-orange wings with distinctive bold black veins and white dots on the black wing borders and on the black body, and look remarkably similar on the underside.  Its larva are striped with yellow, black, and white, and they have two sets of black tentacles rising from their bodies.  

Queens mating, showing their undersides
While the underside of the Queen butterfly can look a lot like a Monarch, it is its upperside that allows for a definitive identification.  Queens can appear almost solid orange compared to stained glass pattern of the Monarch, having rich dark orange wings that lack the black veining and white spots toward the dark wing tips and along their black edges. While adult Queens seek out ageratum, eupatorium, and heliotrope as preferred nectar flowers, adult Monarchs are much broader generalists in terms of their use of many types of nectar plants.

Queen dorsal or upperside, showing white spots along forewing

Soldier dorsal or upperside, showing absence of white spots along forewing
and more obvious wing veining
Soldiers typically occur where Queens are common and are often overlooked due to their very similar appearance.  They can be properly identified by fewer white spots and more obvious dark wing veining on the forewings than on the Queen, but less defined veining than on the Monarch.  Another clue is that Soldiers generally fly in our area in late summer and fall.  Both Soldier and Queen larva are Monarch look-alikes, sporting yellow, black, and white stripes, but with three sets of black tentacles instead of two.

Viceroy dorsal or upperside, showing black band across middle of the hindwing
In an action intended to deceive, the Viceroy (Limenitis archippus) is a milkweed butterfly mimic, using its similar patterning and color to trick predators into thinking it is just as distasteful.  Viceroys are smaller than Monarchs or Queens and usually have a black band across the middle of each hindwing.  This band can be faint or missing, but this butterfly can also be identified by its flying style of quick flaps and flat-winged glides, rather than flying strongly with wings in a shallow V-shape like the Monarch and Queen.  One more way that you can uncover this butterfly’s royal ruse is by knowing that its host plant is willow and not milkweed, and its larva resemble a horned bird-dropping.

Take a closer look the next time you see an orange butterfly on the wing.  It might just be a Monarch heading north, or a Queen or Soldier nectaring on mistflower, or maybe even a Viceroy trying to pull off a royal ruse!