Month: January 2021

By some unusual circumstance, Bug of the Week escapes the chilly confines of the Maryland winter and visits scenic Zion National Park and the Great Basin Desert, where we encounter entertaining and unorthodox darkling beetles called desert stink beetles. You’ll remember last week we met cousins of these gymnastic beetles called forked fungus beetles as they battled for possession of bracket fungi and potential mates. 

On the desert floor as day waned, these large and very juicy scrumptious looking darkling beetles appeared and wandered about feeding on vegetation with impunity. At close to an inch in length, these jet-black behemoths were highly conspicuous against the light red desert earth. With hungry predators such as lizards, birds, and rodents roaming about, the desert is a dangerous place for large, tasty-looking insects. As I crouched to photograph a beetle, it halted, stood on its head and lifted both pair of hind legs off the ground like some contortionist from Cirque du Soleil. What manner of trick was this? As I examined the creature a bit more closely with my fingers, my reward was a distinctly unpleasant odor emanating from the rear end of the bold beetle. Later my fingers turned a curious shade of brown where chemicals squirted by the beetle reacted with the air and my skin. 

Defenses of the desert stink beetle: First, when you see a human with a camera, run for grassy cover. Second, if he has you cornered and pokes at you with his giant finger, stand on your head and kick at him. Third, if all else fails, just lie on your back, legs in the air, play dead, and maybe the idiot will get bored and leave you alone. That worked.

This marvelous denizen of the desert was a darkling beetle in the genus Eleodes. Eleodes has evolved an elegant defense against other animals that would like to make it dinner. Dr. Thomas Eisner discovered that within the abdomen of Eleodes two large glands produce several types of quinones and other organic compounds. These noxious chemicals cause extreme irritation to mucus membranes such as those lining the mouth and eyes of predators like birds and toads. Quinones are also repellent to hard-core invertebrate predators like ants. Eisner suggested that the “headstand” routine may serve as a warning to would-be attackers to leave Eleodes alone or suffer the irritating consequences. It appears that at least one crafty desert predator, the grasshopper mouse, has devised a way to circumvent the beetle’s defense. Upon encountering its prey, the grasshopper mouse flips the beetle around and jams the beetle’s rear end into the soil. With the beetle’s chemical defenses shooting harmlessly into the dirt, the grasshopper mouse consumes the beetle, starting with the head, of course. When it comes to dining on Eleodes beetles, the grasshopper mouse has learned that one bad turn deserves another. 

Acknowledgements

We thank Mike, Brian, Anne, and Jim for the inspiration for this Bug of the Week, and  Dr. Shrewsbury for wrangling stinky beetles. The wonderful book “For Love of Insects” by Thomas Eisner served as a reference for this episode.

This post appeared first on Bug of the Week

Wood is composed of several compounds but, most notably, two really tough polymers you probably have heard of called cellulose and lignin. Fungi are one of but a few organisms able to breakdown these carbon-rich compounds and return these molecules to food webs. Without fungi recycling fallen trees, our forests would cease to exist as the dynamic wonderlands we enjoy today. Fungi turn wood into hyphae and fruiting bodies which in turn become food for creatures higher up the food web, including hundreds of species of insects. This week Bug of the Week dives into the email bag to share some marvelous images of really cool beetles whose lives depend on fungi as a source of food and as a stage for romance.

The forked fungus beetle belongs to a large family of beetles called darkling beetles, Tenebrionidae (previously we met other members of this clan in their winter refuge beneath the bark of a tree).  As their name implies, both larval and adult forked fungus beetles consume and thrive on nutrients contained in the tissues and spores of fungi. Bracket fungi in the genera Ganoderma and Fomes are reported to be favored hosts. Female beetles deposit eggs on the surface of the bracket fungus and larvae tunnel in and feed on nutritive hyphae. The forked fungus beetles we meet today were photographed in September 2020 on the surface of the bracket fungus where courtship battles often take place. The large horns curling above the head of the fungus beetles occur only on males. They play a key role in competitive interactions with other males for opportunities to mate with very cute but hornless female beetles.  Male beetles can often be found guarding bracket fungi where they chase away other males, potential rivals, and thereby monopolize the critical resource needed by females to lay eggs. One study found that males with larger horns had a greater chance of mating success than males with smaller horns.

Combat between two forked fungus beetle (Bolithoterus cornutus) males. The larger attacking male uses his clypeal horns in an attempt to dislodge the smaller male. The smaller male was previously courting the female and during the combat grips her with all six legs. The video has been sped up to 5x actual speed. Please visit the source of this video in the following amazing article: K.M. Benowitz, E.D. Brodie III, V.A. Formica (2012) Morphological Correlates of a Combat Performance Trait in the Forked Fungus Beetle, Bolitotherus cornutus. PLoS ONE 7(8): e42738. https://doi.org/10.1371/journal.pone.0042738

In addition to the prominent horns curling above the head of the male, a smaller pair of horns is present near the eyes at the front of the beetle’s face. So, other than looking marvelous, of what use are the horns? As part of the mating ritual, a male beetle will climb atop his mate and guard his intended for up to five hours while intermittently attempting to mate with her. Scientists have observed amorous male beetles using their two sets of horns “like a wedge and a bottle opener” to dislodge already engaged males from the female and thereby assert themselves as the winning suitor. In this battle to procreate, scientists have found that large beetles, ones with larger horns, are stronger than smaller beetles. Their powerful grip may make big beetles with big horns more difficult to dislodge from their mate than smaller males with puny horns.  In forked fungus beetles and many other animals, yes, size does matter.

Acknowledgements

We thank Cathy Keifer for providing the inspiration and marvelous images used in this episode. The remarkable articles “Morphological Correlates of a Combat Performance Trait in the Forked Fungus Beetle, Bolitotherus cornutus” by K.M. Benowitz, E.D. Brodie III, and V.A. Formica, and “Common name: forked fungus beetle (suggested common name) Scientific name: Bolitotherus cornutus (Panzer) 1794 (Insecta: Coleoptera: Tenebrionidae)” by Ummat Somjee and Andrea Lucky provided information used in this episode. Please learn more about forked fungus beetles at the following links:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0042738

http://entnemdept.ufl.edu/creatures/misc/beetles/forked_fungus_beetle.htm

This post appeared first on Bug of the Week

On chilly days, most small invertebrate creatures like insects are locked in winter torpor awaiting spring’s warmth. However last week, following a nighttime low in the teens and with hoar frost still on the ground, I was delighted to see a gang of pillbugs, a.k.a. rollie pollies, sowbugs, potato bugs, or woodlice, slowly going about their task of recycling organic matter beneath a large bolt of a fallen ash tree. Unlike predators such as lady beetles or praying mantises that occupy exalted places high in the food webs, detritivores occupy lower rungs on the ladder of life. Detritivores are key players in Mother Nature’s clean-up crew. Their important task is to eat dead and decaying things such as fallen plants and return minerals locked-up in leaves, fruits, and woody tissues to the nutrient cycle. We visited other recyclers in previous episodes including rhinoceros beetles, millipedes, termites, and bess beetles.  

Early one morning, with frost still on the ground, a scrum of pillbugs huddles beneath a log. As the early morning sun warms their bodies, fourteen legs help them skitter from the sunlight to find danker refuge beneath the bark.

Isopods are not truly bugs, so please excuse their guest appearance in Bug of the Week, but they are odd and fascinating members of the arthropod clan. They belong to a group of hard-shelled creatures called the crustaceans. Crustaceans include tasty, familiar edibles like crabs, lobsters, and crayfish. Isopods commonly occur in marine environments where they eat algae, diatoms, and decaying vegetation. Eons ago, some adventurous members of the isopod lineage moved from the sea to the land. These explorers were the ancestors of the isopods commonly found beneath logs in the forest and those in my compost heap. Most gardeners know these curious creatures by the names pillbug or sowbug (a closely related terrestrial crustacean). The name pillbug stems from the ability of many species of these isopods to roll into a pill-shaped ball when threatened much like an armadillo. This defensive posture makes the tender underbelly of the pillbug difficult to reach. Armor-like plates on its back shield the pillbug from attack.  

With the return of warm weather, pillbugs will once again begin the important job of recycling my leftover vegetables. And in this taste test, it looks like carrots are preferred to tomatoes.

Pillbugs are common in moist habitats beneath leaf litter, compost, rotten logs, boards, and stones. Moisture is a key element in the life of isopods. Even though they have escaped the confines of a life aquatic with their colonization of land, these true crustaceans still rely on gills for the exchange of oxygen and carbon dioxide and those gills must remain wet. Unusually wet seasons like ones we have experienced in recent years create favorable conditions for explosions of pillbug populations. While pillbugs and sowbugs play an important role as recyclers, when too numerous they may damage the tender roots and stems of plants in greenhouses or gardens. Folks sometimes are dismayed when pillbugs appear in basements or garages as they move about in search of dead things. You can thwart entry of pillbugs into your home by using a few simple tricks: keep mulch away from foundations, maintain door sweeps, and caulk openings to discourage unwanted visitors from entering your home. With the return of warm weather in a few months, my compost heap will be a smorgasbord of rotting vegetables and, without fail, pillbugs will appear from the moldering depths of the bin eager to recycle plant remains. 

 Acknowledgements

We thank Dr. Shrewsbury for wrangling lumber, photographing pill bugs, and providing inspiration for this Bug of the Week.

This post appeared first on Bug of the Week

As we say good riddance to 2020, and welcome in a hopeful 2021, Bug of the Week will spend some time catching up with a few fascinating, fearsome, and funny creatures found in and around our homes. This week we visit tiny recyclers of organic matter called carpet beetles that can sometimes become pests. On a warmish winter day, I occasionally spot a rather lovely small beetle scaling a wall or scooting across a countertop in my home. Carpet beetles get their name from their proclivity to breed in a wide variety of natural substrates containing the protein keratin, which is found in felt, silk, feathers, pet hair, animal hides and carcasses, and, yes, woolen carpets. They become pests when colonizing a drawer, closet, or box where sweaters or other garments are stored. Adult beetles deposit eggs that hatch into hungry, tiny larvae which nibble away fibers, creating holes or sinuous trails in fabrics.

The larvae are very hairy little beasts, covered with long hairs or setae. Prolonged exposure to these hairs festooning the bodies of carpet beetle larvae has caused dermatitis in some people. Carpet beetles belong to a larger clan of recyclers called dermestids, or hide beetles. Hide beetles provide an important service to museum curators by virtue of their ability to strip skeletons of virtually all muscle and sinew, producing lovely bare bones. However, dermestids create problems for professional and amateur entomologists when they invade collections of pinned and preserved specimens. Larvae bore into dead insects and consume proteinaceous tissue within.  As they feed, small pellets of waste products called frass litter the area beneath the infested specimen. This is the classic hallmark of a dermestid attack. 

During winter, pretty carpet beetle adults and their very hairy larvae sometimes wander about my desk, table, and walls. In the wild, other dermestids are some of the last visitors to animal carcasses. Larvae like this one can remove skin, muscle, and other connective tissue, leaving behind nothing but bone.

Thwarting carpet beetle infestations is relatively straightforward. Before storing any garment made of natural fibers be sure it is laundered or dry cleaned and stored in a sealable bin or bag. If these rascals have already established a foothold somewhere in your home, try to ferret out their location. This could be a seldom used woolen rug in the basement, a box of sweaters in the attic, or a blanket, dress, or sport coat in a closet. Carpet beetles can also breed in carcasses of dead insects so maybe a pile of dead stink bugs in the attic is the source of an infestation. Some species of dermestids breed in stored products like grains, pet food, nuts, and spices. We met a caterpillar with similar habits, the Indian meal moth larva, in a recent episode. Once you locate the infestation, discard or destroy the material serving as the source of the infestation. In the case of carpets and rugs, vacuuming and deep cleaning will help. A lightly infested blanket or scarf can be salvaged by either placing the item in a deep freezer that is below 0 degrees Fahrenheit for several days, or by heating it above 130 degrees Fahrenheit for several hours. Temperature extremes can kill eggs, larvae, pupae, and adult carpet beetles. But please don’t set the item on fire or burn your house down.

How does a person who should know better wind up with carpet beetles in a home? The answer lies in the back of a closet where show-and-tell bugs used in STEM outreach are stored. In a tray of preserved scarab beetles, one unfortunate specimen bears an untidy deposit of frass attending its rear-end.  Since dead beetles don’t engage in post-mortem voiding of waste, the pile of frass is the tell-tale signature of carpet beetle larvae dining inside the dead scarab. Bad luck for the scarab translates to good luck for sharing a tale of carpet beetles.    

Bug of the Week wishes everyone a happy and healthy New Year free of all plagues!

Acknowledgements

 Information in this episode originated in great articles written by Whitney Cranshaw at Colorado State University and Michael Potter at the University of Kentucky. Learn more about these creatures at the following websites:

https://extension.colostate.edu/topic-areas/insects/carpet-beetles-5-549/

https://entomology.ca.uky.edu/ef601#:~:text=University%20of%20Kentucky%20College%20of,feathers%2C%20skins%2C%20and%20leather

This post appeared first on Bug of the Week