Focusing in on arthropods of the West

Up-close portraits of jumping spiders, beetles, Mormon crickets and other creepy-crawlies essential to our ecosystems.

 

Summer in the American West is rich in spectacle, from towering, snow-crowned mountains and lightning-loaded cloud heaps to floral fireworks in alpine meadows and riverine parades of migrating elk. Often, these visual joys are rooted in panorama; scenic vistas of activity captured best at a wide angle. But zooming in has its rewards too: an army of jointy-footed mini beasts, as beautiful and intriguing as larger, furred and feathered wildlife.

Consider tiger beetles: common Western insects often found whizzing along sandy trails and riverside beaches. The beetles are frustratingly hard to catch. But a little patience and some elbows-in-the-dirt positioning reveals a creature as remarkable as any bear or bison, a carnivore characterized by mean-toothed jaws, bugged-out, chasm-black eyes, and wing covers as richly metallic as any sports car.

But the value of arthropods goes beyond visual charms. Insects, for example, provide a range of ecosystem services—from dung burial and carrion breakdown to stream cleaning and pollination—that, according to entomologist John E. Losey and Mace Vaughan, co-director of the Xerces Society’s pollinator program, add nearly $60 billion per year to the U.S. economy alone.

Best of all, fascinating arthropods are not limited to lush tropical jungles. They are everywhere and all around. Whether they’re skimming a rain puddle’s ephemeral mirror or feeling out the nightglow of a porch light, arthropods are utterly accessible to all. Just focus in.

Marian Lyman Kirst

Jumping spiders make ideal arachnid ambassadors, what with their charmingly goggle-eyed, seemingly mustachioed mien, not to mention the rave-worthy dance moves that courting males employ to seduce mates. These common, generally fuzzy spiders often boast intricate abdominal patterns, brightly hued facial patches and metallic “jaws” or chelicerae.

Jumping spiders do not build webs to catch prey. Instead, they’re active daytime hunters that use their well-developed hind legs to leap (often many times their own body length) at prey, which they target and catch using their extraordinary eyesight, some of the keenest of all invertebrates.

This species is likely Phidippus audax, a common and widespread North American jumping spider.

Marian Lyman Kirst

Carrion beetles belong to one of the many insect battalions that assist a larger army of invertebrate scavengers in helping to break down dead and decaying organic matter, enabling its eventual return to the ecosystem.

Female carrion beetles lay their eggs in the warm earth around a carcass. When the eggs hatch, the larvae — which resemble tiny trilobites — feed on the carcass and then pupate in the surrounding soil. Adults feed chiefly on the carcass’ multitudes of carrion-feeding fly larvae, controlling maggot numbers.

The above photo shows two different carrion beetle species that were found together on and beneath the carcass of a small field rodent: (left) the northern carrion beetle (Thanatophilus lapponicus) and (right) a margined carrion beetle (Oiceoptoma noveboracense). Both are widespread in North America; but T. lapponicus is particularly important in the West because it’s a cold-adapted species that is often the sole carrion beetle in the region’s high mountain habitats.

Marian Lyman Kirst

Mormon crickets are not true crickets but a type of shield-back katydid, a member of the family Tettigoniidae. These katydids feature in a classic Western legend in which ravenous hordes of these bulbous, herbivores nearly wipe out the crops of early Mormon settlers before a hungry flock of gulls comes to the rescue.

Indeed, Mormon crickets have a long history in their native West — not only as crop-eaters, but as food for humans themselves. Archaeologists discovered the roasted remains of hundreds of Mormon crickets in an ancient cooking pit inside a cave in northern Wyoming.

Mormon crickets live only in the Western U.S. and can range in color from red to green to brownish yellow. They are often found moseying through sage-brush-speckled rangeland and forb-rich forests, but resident populations also commonly “potter”(move about at random) in alpine tundra at elevations higher than 8,000 feet. Although Western North America hosts more than 100 species of ground-dwelling, shield-back katydid, the name “Mormon cricket” generally refers to just one, Anabrus simplex.

Marian Lyman Kirst

Butterflies in the family Pieridae, which includes the marbles, orangetips, sulphurs and whites, are among spring and summer’s most common and popular Lepidopterans. One of the most ubiquitous Pierid butterflies is the non-native cabbage white — a summer resident of parks and backyard gardens that was introduced to North America from Europe in the 1800s. The West is home to a number of native whites as well, including the checkered, western and spring white butterflies.   

This pictured species is likely a spring white (Pontia sisymbrii), which is found throughout the Western U.S. and often seen flitting about coniferous forests, above dry desert slopes and through rocky canyons.

Marian Lyman Kirst

Tiger beetles are flash-quick predators. In fact, when hunting, they are so fast they suffer periods of temporary blindness as their eyes fail to collect enough photons to form images of their quarry. To compensate, the beetles stop, mid-chase, for a split second to re-orient, resulting in a distinctive red light/green light style of movement.

The above creature, likely Cicindela repanda (the bronzed tiger beetle), was found skittering atop a run of riverside dunes — common  habitat for many Western tiger beetle species.

Marian Lyman Kirst

There are more than 400 species of blister beetles in North America, but they’re particularly diverse in the Western U.S. The insects get their name from the skin-blistering, cantharidin-infused secretions they release from leg joints when handled roughly or squeezed. That's why some are brightly colored or patterned. These oil beetles, however, are leathery, bloated and shoe-polish black. They are ground-dwellers and cannot fly. Their elytra, or hardened wing covers, are reduced to short, petal-shaped nubs.

Some oil beetles in the genus Meloe, such as those pictured above (possibly Meloe impressus), display noticeable physical differences between the sexes: The females are often much larger than the males, and lack the thickened antennal elbows that the males possess.  The males use these kinks to hook onto and hold the antennae of females during pre-mating courtship displays.

Marian Lyman Kirst

Water measurers (or marsh treaders), despite their twiggy resemblance to walking sticks, are actually semi-aquatic true bugs in the Hydrometridae family of the order Hemiptera. At 8-12 mm in length and with needle-slim bodies and legs, these wispy insects deftly patrol the surface of ponds and vernal pools in search of small invertebrates, which they attack using strong but stylus-slender mouthparts.

Marsh treaders are often confused with another Hemipteran, the fully terrestrial thread-legged assassin bug. The water measurer, however, is distinguished by its elongated head and smooth forelegs, whereas thread-legged bugs (members of the Reduviidae family), tend to have shorter, blunter noggins and spiny, mantid-like forelegs. The above specimen is likely Hydrometra australis, a mostly Southern and Western species.

Marian Lyman Kirst

North America’s 18 species of snakeflies occur almost exclusively in the West. These lively predators get their name from the adults’ elongated “necks” and long, narrow bodies. However, the snakefly’s worm-like larvae are equally serpentine and move with a distinctive slither.

The adults can be observed throughout the summer and fall, often perched on or near flowering plants and bark, or in leaf litter, where they hunt small prey.

Female snakeflies, like the one pictured above (from the genus Agulla), have long, tail-like ovipositors, which they use to insert eggs into plant tissue. This projection is often mistaken for a stinger. However, snakeflies are harmless to people and help control insect pests such as aphids.

Marian Lyman Kirst

The red flat bark beetle’s name gives an apt description: They are ruddy to reddish-tan and are painfully compressed, a physical adaptation that may help the adults navigate narrow fissures and cracks within the wood and beneath the bark of deciduous trees where the beetles track down arthropod prey. These relatively common insects (from the beetle family Cucujidae) are also some of the most cold-hardy animals on Earth.

The larvae of the Western red flat bark beetle subspecies, C.c. puniceus, which ranges from the Pacific Coast to above the Arctic Circle, draw on a combination of freeze-avoidance mechanisms, including the production of cryoprotectants (like glycerol) and antifreeze proteins, extreme dehydration, and a period of reduced metabolism to regularly survive temperatures as low as -58 degrees Celsius. This process is called ‘supercooling’ and it allows the beetle’s body fluids to chill below the freezing point of water without turning to ice.

Researchers at the University of Alaska in Fairbanks recently discovered that some of these same larvae can actually supercool to and survive exposures of -100 degrees Celsius. They accomplish this by, essentially, turning to glass. At temperatures around -58 degrees Celsius, the beetle’s body water transitions to a non-crystalline, glass-like state, which, combined with its freeze-avoidance mechanisms, allows the insect to endure the desperately cold temperatures involved in overwintering beneath the bark of deadfall and standing trees in its most northerly habitats.

Marian Lyman Kirst

This beetle’s robust, protruding jaws and long legs are not just for show. These enthusiastic and effective predators belong to the Carabidae family of beetles, which are collectively known as ground beetles. During daylight hours, these insects are usually found under rocks, logs, leaves or sod. But come evening, most carabids emerge from their hideouts to furiously pursue their dinner.  Some species are considered highly beneficial, especially in gardens, as they prey on slugs and other plant pests.

Carabid beetles are generally black but sometimes boast rich metallic sheens and bumpy texturing on their upper surfaces. Witness the golden-bronze burnish on the specimen picture above, possibly Carabus maeander.

Marian Lyman Kirst

This handsome insect is known as an eyed elater, a large (19-44 mm-long) member of the family Elateridae (the click beetles). Eyed elaters (genus Alaus) are characterized by large black thoracic eyespots and are found throughout North America with the species Alaus melanops more common in the West.

Click beetles, sometimes called skipjacks, have an unusual escape strategy. When threatened or roughly handled, a click beetle thrusts a spine-like peg on the underside of its thorax into a notch on its chest with enough force and speed to propel the insect into the air and, ideally, away from its antagonists. The beetle also uses this maneuver, which produces a loud clicking sound, to right itself should it get flipped onto its back.

Marian Lyman Kirst

Assassin bugs are aptly named: Fast and powerful, they attack and stab their victims — generally other invertebrates, some of them much larger — with distinctive, curved, three-segmented beaks. While at rest, the bug tucks this nasty weapon into a groove on its chest. 

The above insect (likely Fitchia aptera) belongs to a small group of assassin bugs composed of just two North American species that include both winged and wingless adult forms. In the West, look for this assassin bug beneath rocks and cowpies in arid and rangeland habitats.

All of the pictured specimens were photographed alive and were found in south-central Montana and northern Wyoming by Marian Lyman Kirst, a free-lance science writer, photographer and former HCN intern based in Billings, Montana. She is currently working on a master's degree in entomology through the University of Florida. Thanks to Ralph Scott and Dr. Lisa Taylor for their help with specimen identification.