The recession has slowed housing starts, but builders of clay dwellings remain busy. Millions of clay homes are built this and every summer in Utah. These dwellings can disintegrate in a summer cloudburst, so you’ll find them beneath overhangs like rock cliffs, or under bridges and the eaves of your house.
These free-standing mud homes are built by a few dozen species of solitary bees and wasps. Among them is the mud dauber, Sceliphron caementarium, a big leggy wasp found throughout Utah. The female wasp constructs hollow clay units one at a time, each the dimensions of a pitted date. The mother mud dauber gathers the wet clay in pellets. At the nest site, she draws the pellet into a ribbon of clay which becomes the next arch of the tubular nest. While working the clay, she audibly buzzes her flight muscles. This vibration visibly liquefies the clay for a few seconds. This strengthens its bond, much as workers in concrete do using large vibrating probes.
The mother wasp then collects spiders, often plucking them straight from their webs after a pitched battle. She permanently paralyzes each spider using her venomous sting. The venom is not lethal. Rather, it is paralytic, keeping the spider alive and fresh but helplessly immobile, a gruesome spider buffet for her grub-like larva to eat. Each hollow nest is packed with a half dozen spiders, one of which receives her egg. In a few weeks time, the growing wasp larva finishes eating its buffet and pupates, becoming dormant for the winter.
Nest building and provisioning by these wasps is a complex result of heritable instincts tailored to local circumstances by learning. It is also a rare trait among insects, most of whom simply lay their eggs and leave. Through observation and manipulative experiments, students of animal behavior have investigated mud-building wasps for well over a century. If you have mud daubers around your home, grab a cool drink, pull up a chair, and enjoy watching their home-making labors.
This is Linda Kervin for Bridgerland Audubon Society.
Credits:
Images: Courtesy & Copyright Jim Cane, Bridgerland Audubon Society
Text: Jim Cane, Bridgerland Audubon Society
Katydid Courtesy Stokes Nature Center Scott Biggs, Photographer
Monarch Butterfly Courtesy Utah Division of Wildlife Resources J. Kirk Gardner, Photographer Licensed Under CCL 3.0
Tiger Swallowtail Butterfly Courtesy Utah Division of Wildlife Resources J. Kirk Gardner, Photographer Licensed Under CCL 3.0
Insects are the most diverse class of organisms on earth, with more than 900 thousand known species. With that many different kinds of bugs, it’s no wonder that they take on such a vast array of shapes, sizes, and colors. From Luna moths to fruit flies to millipedes, the diversity of this class of life is immense. Some insects have developed a shape and coloring so deliberate that it’s almost astounding. These insects are mimics – bred to look like something they aren’t, in an attempt to get a leg up on the survival game.
Insects can mimic all kind of things – stick bugs, for example, make such convincing twigs that you’ll never know they’re around until they move. Katydids look just like bright green leaves, and there are some species of caterpillar that in their youngest stages look just like splatters of bird droppings. But the mimics that I find most interesting are those who mimic other insects.
There are two main types of insect-to-insect mimicry. Batesian mimicry occurs when one harmless species mimics another dangerous one. Species that look like something fierce can capitalize on that insect’s dangerous reputation and potentially be safer from predators because of it. A common Utah pest, the peach tree borer, is a moth that very closely resembles a wasp in both its morphology and behavior. Harmless, nectar-eating hoverflies exhibit the black and yellow body stripes of a bee. Apparently, it’s not just humans who want to stay away from the business end of a wasp or a bee – many insect predators, too, give them a wide berth.
Ants also have a fierce reputation in the animal world, and so attract a lot of mimics. A number of spider species not only mimic ants in morphology and behavior, but some also give off ant pheromones, making them smell like friend rather than foe. While many ant-mimicking spiders go undercover as a way to hide from their own predators, some do use their disguise as a way to access the nest of their prey.
Batesian mimicry is a delicate balance. Predators need to catch a wasp or two before they associate that color pattern with dangerous prey. If there are too many tasty mimics around, the predators will stop associating black and yellow stripes with a dangerous object and the mimic’s ploy would fail to work.
A slight variation on Batesian mimicry are insects with false faces and false eyes. Tiger swallowtails – those large yellow and black butterflies – have red and blue spots on each of their hind wings at a place farthest from their body. These spots, combined with the skinny black ‘tails’ from which the species gets its common name, are meant to look like the eyes and antennae of another, possibly larger and more fierce, insect. This imagery is meant to frighten off predators, but also in the case of an attack, to spare the most important part of the butterfly’s body.
The second, less common, form of insect-to-insect mimicry is called Müllerian mimicry. This occurs when two equally distasteful insects come to resemble one another. Most of us are familiar with the monarch butterfly. As caterpillars, they feed exclusively on toxic milkweed. The caterpillars take the toxins into their bodies and retain them as adults, making them not only bad-tasting but also poisonous. Predators have learned to associate that distinct orange and black wing pattern with a bad experience, and therefore leave them alone. Viceroy butterflies look incredibly similar to monarchs – the only difference being an extra line of black on the hindwings of a viceroy. While once thought to be Batesian mimics, recent studies have shown that viceroys are equally unpalatable. Their similarity in looks to monarchs, then, serves to reinforce the distasteful nature of both species.
Mimicry is of course, not restricted to the insect kingdom. Some plants have gotten into the mimicry business in order to trick insects. The hammer orchid, which grows in Australia, has a flower that mimics a female bee. Male bees, in mistakenly trying to mate with the flower, collect pollen that they then carry with them to the next, ensuring pollination of this sneaky plant. So this ingenious tactic some insects use to gain a leg up in the game of survival can also be used against them to the advantage of others. Isn’t life amazing…
For more information and photos of some insect mimics, visit our website at www.wildaboututah.org. For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.
Many thanks to Don Viers for his input on this piece.
Credits:
Photos: Courtesy and copyright as marked
Text: Andrea Liberatore, Stokes Nature Center
Additional Reading:
Imes, Rick (1997) Incredible Bugs: The Ultimate Guide to the World of Insects. Barnes & Noble Books. New York, NY
Pyle, Robert Michael (1981) National Audubon Society: Field Guide to Butterflies, North America. Alfred A. Knopf. New York, NY
Viers, Don (2013) Personal conversations
Ritland, David B., Brower, Lincoln P. (1991) The Viceroy butterfly is not a Batesian mimic. Nature, vol. 350, 497-8. Available online at: https://www.nature.com/nature/journal/v350/n6318/abs/350497a0.html
Cushing, Paula E. (2012) Spider-ant associations: An Updated Review of Myrmecomorphy, Myrmecophily, and Myrmecophagy in Spiders. Psyche, vol. 2012. Available online at: https://www.hindawi.com/journals/psyche/2012/151989/
Miller Moth/Army Cutworm Adult Euxoa auxiliaris Courtesy IPMimages.org/bugwood.org Whitney Cranshaw, Colorado State University, Photographer
Miller Moth/Army Cutworm Adult Euxoa auxiliaris Courtesy IPMimages.org/bugwood.org Whitney Cranshaw, Colorado State University, Photographer
Miller Moth/Army Cutworm Larva(e) Euxoa auxiliaris Courtesy IPMimages.org/bugwood.org Frank Peairs, Colorado State University, Photographer
Hi, I’m Holly Strand from the Quinney College of Natural Resources at Utah State University.
World Cup Colombian soccer player James Rodriguez isn’t the only one with a flying insect problem. For several weeks many Utahns have been coping with a bumper crop of miller moths. These dusty gray nuisances have been mobbing our lights, dive bombing our heads and plopping into our nightstand water glasses. Miller moth annoyance levels seemed highest along the Wasatch Front but other areas experienced high numbers as well.
Miller moths begin their lives as army cutworms. The larvae eat their way through the winter chomping on winter wheat, alfalfa, and many other types of crops and plants. After eating all winter, the army cutworms burrow into the ground to pupate. They emerge six weeks later with a yen for flower nectar. This sets them migrating to the alpine elevations of the Wasatch and Uinta Mountains. However, flowery trees and gardens along the Wasatch front are powerful diversions; thus our yards function as filling stations along the miller moth migration route.
Army cutworm populations soar during relatively warm winters with little snow cover. And that’s what happened this year in the south central counties of Utah. And that’s why we have so many moths now. But to keep this issue in perspective—know that the numbers we see in UT are nothing compared to the annual invasions experienced by populations on the Rocky Mountain front range. In Denver, annual spikes in vehicle crashes, therapist visits and broken light fixtures clearly coincide with the influx of miller moths.
Luckily, the moths are no more than a nuisance – they won’t eat your food or damage clothing or upholstery. And while sometimes it seems as if they are targeting your head, they really aren’t. If they are in your house, it’s because they were seeking shelter from the daytime predators by seeking a dark crack or crevice to crawl into—and then got into your house by mistake.
If you swat these unfortunate moths, they’ll get back at you. They leave a dusty gray, powdery mess. The powdery dust is really the moth’s tiny scales and is what gave the moth its name. For these scales are reminiscent of the dusty flour that covers the clothing of someone who mills grain.
For a clean resolution to the problem, veteran miller moth killers from Colorado suggest you suspend a light bulb over a bucket of soapy water. Moths will flick off the bulb into the water. At our house we catch them with a butterfly net and set them free outside. For I imagine that they will be off to the mountains as quickly as possible after that experience.
In early fall, the moths return to lower elevations to lay their eggs. Enough have died during the summer so we won’t notice them much if at all. But if next winter is also mild, we will be hosting our miller moth friends again.
Thanks to USU biologist Diane Alston for sharing her entomological expertise.
For pictures, sources and tips for living with miller moths, go to www.wildaboututah.org
For Wild About Utah, I’m Holly Strand.
Credits:
Images: Courtesy IPMimages.org/bugwood.org & Colorado State University Extension, Whitney Cranshaw and Frank Peairs, Photographers
Text: Holly Strand
Utah has neither snapping turtles nor snapping shrimp, but we do have snapping grasshoppers. Their loud crackling sound punctuates summer hikes along open canyon slopes and rocky mountain ridges. (recording of a snapping grasshopper) Like other band-winged grasshoppers, they are named for the arcs of muted color across their hind wings.
But it is the male’s insistent racket that draws our attention. A snap results when a stout vein of their hind wings is flexed between two positions. That flexure alternately stretches and relaxes the membrane between the veins, something like an umbrella being popped open and then folded. The vein flexure generates an audible snap, like a dog’s training clicker. (recording of dog clicker) The grasshopper’s loopy flight generates a train of snaps. (recording of snapping grasshopper)
Crepitating cicadas have a similar means of sound production. They click from a perch on a plant stem. (recording of cicada) Their clicking has filled the air of northern Utah this summer.
As with cicadas, it is the male band-winged grasshopper that snaps to woo a mate. He displays solitarily during flight, the longer advertisement the better, apparently. Hopefully, an attracted female will meet him in the air. Sadly for the male, most of the time no female responds and he lands unrequited. There the previously conspicuous male seems to silently vanish, so perfectly does his mottled tan camouflage match bare ground. After resting a bit, he launches again to resume his crackling display.
Species of band-winged grasshopper differ in their snapping displays, which a female no doubt appreciates. But for you and I, it is enough to know that we are hearing snapping grasshoppers on a warm day’s hike.
Pupa of
