Mate Guarding and Oviposition in the White-spotted Sawyer, Monochamus scutellatus (Coleoptera: Cerambycidae)

Please do not let the title of this post intimidate you. This would be a typical title for a paper in a scientific journal, but I promise to keep the language understandable, lively, and captivating. I also hope that you will be more likely to visit scholarly publications to learn more about the insect or arachnid subjects that interest you.

An impressive male M. scutellatus

I had the good fortune of stumbling upon a small sawmill in Black Forest, northeast of Colorado Springs, in June of 2016. The property owners, perhaps begrudgingly, gave me permission to look for insects in the stacks of Ponderosa Pine logs there, and it proved to be a "Beetle Bonanza." I visited on several occasions and found scores of jewel beetles (Buprestidae), longhorned beetle (Cerambycidae), checkered beetles (Cleridae), and a few bark beetles (Curculionidae: Scolytinae).

Among the more abundant species among the logs was the White-spotted Sawyer, Monochamus scutellatus. These are fairly large insects, 15-27 millimeters in body length, and members of the longhorned woodborer beetle family. The long "horns" refer to the antennae of these beetles. Males have antennae that may be twice the length of their bodies or even longer. The front pair of legs is also longer than in the females, and the front tarsi ("feet") are expanded to better grip the female during mating.

Male guarding a female

What I observed in one pair of sawyers prompted me to read about the mating behavior of the species, if only to confirm my hypothesis that the male guards the female he has mated with to prevent rival males from usurping his genetic investment in her offspring. It turns out there is even more to the story than I imagined, and I hope to observe those other behaviors at some point, too.

White-spotted Sawyers breed in dead, dying, injured, fire-scorched, or recently-felled pines, true firs, and Douglas fir, and spruce. Such resources are rather scarce in a forested landscape, so it pays males to stake them out with the understanding that eventually females will visit in order to lay their eggs (oviposit). Surprisingly, the males emit a pheromone that draws additional males to an oviposition site. The airborne chemical cue is called an "aggregation pheromone." Despite their size and ungainly antennae and legs, sawyers are accomplished fliers and easily make their way to the source of the pheromone.

Jaws of female Whitespotted Sawyer

Once there, the largest males with the longest antennae may square off in one-on-one duels for possession of the oviposition resource, which is the area of the tree trunk with greatest circumference. They lash at each other with their oversized antennae, and may grapple by locking their jaws and biting. Smaller males generally back off, giving way to larger rivals based on antenna-length alone. The dominant male mates with incoming females that may then disperse to lay their eggs. This is not what I observed, but the reference I am reading goes on to describe what I did record.

Mating, while female chews oviposition hole

I witnessed copulation between a male and female M. scutellatus, during which time the female was "multi-tasking," chewing a small cavity in the bark. At the conclusion of mating, the female turned around to deposit at least one egg in that cavity while the male continued to grasp her in a loose but protective embrace. She then turned again and appeared to resume chewing the bark cavity, but perhaps she was grinding sawdust to cover her egg.

Female ovipositing while male guards her

Fret not about the smaller male beetles, they may achieve mating success by protecting a less optimal tree bole; and they may profit from the expensive production of aggregation pheromone by other males. Smaller males are usually more agile and vigorous than their larger conspecifics.

The entire life cycle of the White-spotted Sawyer takes from one to two years as the larva that hatches from the egg bores first under the bark, then tunnels deep into the wood, sometimes reaching the heartwood. It eventually pupates in a cell near the surface, metamorphosing from a larva into an adult beetle. Once it leaves the pupa, it remains in the pupal cavity while its new exoskeleton hardens. It then chews its way to freedom, a journey that is clearly audible to the human ear.

Female resumes gnawing, covering her egg?

It is important to note that this species, like the overwhelming majority of other longhorned beetles, is not a forest pest. Yes, it can negatively impact logs in situations like the sawmill, before they are cut, but they do not kill living trees outright like the invasive Asian Longhorned Beetle, Anoplophora glabripennis. Sawyers are an important and charismatic part of the invertebrate fauna in coniferous forests across Canada and the northern U.S., and major mountain ranges farther south.

Sources: Coin, Patrick. 2004. "Species Monochamus scutellatus, Whitespotted Sawyer," Bugguide.net
Furniss, R.L. and V.M. Carolin. 1977. Western Forest Insects. Washington, DC: U.S. Department of Agriculture Miscellaneous Publication No. 1339. 654 pp.
Wang, Qiao (editor). 2017. Cerambycidae of the World: Biology and Pest Management. Boca Raton, Florida: CRC Press. 628 pp.

Insects in the News

One of my unfortunate duties as a blogger of truth and science, here and at Sense of Misplaced, is that I must occasionally dispense bad news. There are plenty of awful stories these days, but bear with me and I'll conclude with something uplifting.

The insect story getting the most press right now, by far, is the "Insect Armageddon" opinion piece in the New York Times, and the follow-up article about the German citizen scientists who made the observations. It appears that there has been a precipitous decline in insect abundance in many parts of Europe, up to 75% over the last twenty-five years. Should the numbers hold up to repetition, this is indeed alarming, if not catastrophic. Insects are the foundation of all major biological processes. You can do the math, use your imagination, and draw the obvious conclusions.

There are plenty of places to point blame for the demise of insect populations, and wildlife declines in general, but accusations and rhetoric are not likely to reverse the course of events. We have to act personally, and locally, to go about changing things for the positive. That means resisting the urge to grab the over-the-counter insecticides, planting native trees, shrubs, and flowers in our urban and suburban landscapes, growing our own vegetables without using chemical treatments, putting up "bee condos" for solitary bees....There is no end to what we can do, and it does make a difference. You are setting an example, for one thing.

jAmerican Burying Beetle, © EcoArkansas.com

Meanwhile, our very own government agencies are against us here in the U.S. Make no mistake about it, the current edition of the federal administration is out to ruin public lands in many ways. I already wrote about U.S. Fish & Wildlife granting permission for the construction of a strip mall known as "Coral Reef Commons" on globally endangered pine rockland habitat near Miami, Florida. The President's directive to shrink Bears Ears National Monument and Grand Staircase-Escalante National Monument is further proof of the overriding policy to open public lands to private interests, namely those in the natural resource extraction industries.

It is also quite probable that a lawsuit filed by The Independent Petroleum Association of America, American Stewards of Liberty, and Osage Producers Association will result in the de-listing of the endangered American Burying Beetle, Nicrophorus americanus. This is in spite of the fact that there is grave concern as to whether the species is truly "recovered." It is found only in a handful of isolated locations whereas its historical range was over most of the eastern U.S. It also remains largely a mystery as to why it disappeared in the first place. Until a better understanding is reached, any action toward removing the species from the endangered list is premature at best, and irresponsible at the least. God forbid any creature, Native American population, or other sacred entity stand in the way of short-term profits for greedy corporations.

Oh, well, two can play the lawsuit game, and recently the National Butterfly Center in Mission, Texas filed suit against the federal government to block construction of the border wall, which would cut right through that private preserve. Take that! I have visited this area and can attest to the rich diversity of all organisms there, thanks to the caretakers who are so devoted to it. Many, if not most, United States records for mostly Mexican butterfly species are recorded from the National Butterfly Center. It is on every naturalist's bucket list of places to visit. A wall cannot be erected there, or through the Santa Ana National Wildlife Refuge....

Bee-mimicking clearwing moth, Heterosphecia tawonoides, © Marta Skowron Volponi

Ok, I promised some good news, and here it is. It was recently revealed that a spectacular species of clearwing moth was rediscovered after a gap of 130 years in the scientific record. Known previously from only a single specimen housed in a museum in Vienna, Austria, Heterosphecia tawonoides was observed in the Taman Nagara rainforest of Malaysia. It just goes to show how little we know about a planet we are hell bent on destroying in the name of "progress."

Resolve for the new year to get involved, get outdoors, document, record, and report what you find. You never know where your personal discoveries will lead; or whether you are the only thing standing between a lone population of some creature and its potential extirpation. I'm facing that right now myself, but more on that later.

Losing the Pine Rocklands

It has not been my intent to deprive you of new content on this blog, but personal realities have dictated that I put my energies elsewhere, or have actively blocked my creative mindset. My internal motivations have been dealt devastating blows by external events that leave me wondering if I am making a difference. Meanwhile, I still deal with financial struggles and my aging father's circumstances.

The last (or at least latest) straw is what happened this week with U.S. Fish & Wildlife approving construction of a Walmart and strip mall on one of the last large parcels of imperiled pine rocklands habitat near Miami, Florida. Bulldozers began their devastation on Thursday, but thanks to a lawsuit by the Center for Biological Diversity, and a court order issued by heroic U.S. District Judge Ursula Mancusi Ungaro, the engines of destruction have been shut off, at least for the time being.

The Atala butterfly, © Jaret C. Daniels

This dire situation, to be fair, is the end result of poor management by a number of property players. According to Save The Pine Rocklands, the Richmond pine rockland tract was formerly owned by the University of Miami, which acquired the area for free as military surplus land, in 1981 and 1997. The university then sold eighty-eight acres, for $22 million, to Ram Realty Services in 2014. It is Ram that is behind the "Coral Reef Commons" project that would include a Walmart, LA Fitness, Chick-fil-A, and Chili's; plus a 900-unit apartment complex. A mere 40 acres would be spared as a "preserve."

Since this habitat depends on regular fire events for its existence, one has to wonder how apartment residents and business patrons would tolerate prescribed burns for ecosystem maintenance. That is not to mention whether the forty acres falls below some minimal territorial threshold for which a species could no longer survive. It also bears consideration whether pressure for continued economic development would not eventually compromise the rest of the property. You did it once, so you have set a precedent.

Miami Tiger Beetle, © Chris Wirth at Cicindela@wordpress.com

The pine rocklands are home to a diverse and unique assemblage of organisms, including critically endangered species. Among those are the Miami Tiger Beetle, Cicindelidia floridana, found nowhere else on Earth. The Atala (Eumaeus atala) and Bartram's Scrub-hairstreak (Strymon acis), both butterflies, also exist in no other ecosystem. Florida Bonneted Bat is also at risk. Thirty-one plant species occur there exclusively; and a total of nine federally endangered species call the pine rocklands home.

This is just the latest crime against our natural heritage as the President and his appointees go about dismantling all environmental, consumer, and labor protections for the benefit of an extreme minority of extremely wealthy individuals and corporations. This not politics, it is policy. Very, very bad policy that will negatively impact you, personally, at some point.

Bartram's Scub-hairstreak butterfly, courtesy of U.S. Fish & Wildlife Service and Biodiversity.org

The recent actions by the U.S. Department of the Interior, where the National Park Service and U.S. Fish & Wildlife agencies reside, have been decried as "dereliction of duty," but that is being too polite. This is outright theft of public lands and should be prosecuted as such. It is not failure to fulfill institutional mandates, it is criminal behavior.

I pride myself on presenting you with an unbiased, apolitical blog here, but I have my limits of tolerance. Those limits have been vastly exceeded over the last few months, and I do not foresee improvement any time soon. I hope you will respect my personal desire to protect your right to your "pursuit of happiness" as it involves observing and enjoying the natural world in intact ecosystems. I also urge you to stay silent no longer. Thank you.

Being Thankful for Bugs

This is a repost from November 28, 2014, but it still applies today; and not just for the American holiday of Thanksgiving, but for every day in every location on the globe. Life as we know it would not be possible without insects and their kin.

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A couple days ago the following post crossed my Facebook newsfeed, and it is an excellent reminder of why insects and other arthropods are so important to us as human beings, and to the planet Earth as well.

Honeybee pollinating flower in Arizona

"Thanksgiving is tomorrow …and we all have much to be thankful for. But don’t forget to thank our pollinating friends (bees, beetles and a host of other critters) that provide 1 out of every 3 mouthfuls of food and drink we consume. Without them, and the invaluable service they provide, our lives and our world would be drastically different. Happy Thanksgiving!"

Ecosystem Services

Beyond pollination, insects and related invertebrates furnish many other "ecosystem services" that we can't easily put an economic price on. They are responsible for seed dispersal in many plants. They are at the front lines in the decomposition process for all organic matter be it animal or vegetable. Their activities aerate and mix the soil. They serve as the basis of the food chain, feeding other invertebrates and many vertebrates from fish to birds to bats to aardvarks and anteaters.

Dung beetle pair rolling dung ball in Kansas

A scientific article was published in 2006 in the journal Bioscience that attempted to quantify just four of these ecosystem services: pollination, pest control in croplands, waste (dung) removal on rangeland, and food for wildlife (recreational hunting, fishing, birdwatching, etc). The carefully calculated estimate of the value insects thus provide, in the United States alone, was a staggering sixty billion dollars ($60,000,000,000).

Golden-winged Skimmer dragonfly in GeorgiaWatchable Wildlife

Insects are quickly becoming "watchable wildlife" in their own right. Countless field guides and online resources cater to those who enjoy observing butterflies, dragonflies, moths, tiger beetles, and nocturnal "singing insects" like katydids and crickets. What will the next craze be? It is clear that these communal passions are not only sustaining themselves, but actually growing in popularity, as witnessed by the explosion of National Moth Week, for example. There are festivals for everything from butterflies to bees, even mosquitoes (in Paisley, Oregon).

Drosophila "fruit fly" in ColoradoResearch and Medicine

Insects and other arthropods are also used extensively in scientific research and medicine. We owe much of our knowledge of genetics to research conducted on "fruit flies" (Drosophila spp.) and flour beetles (Tribolium spp.). Fly larvae are used to clean wounds because they carefully avoid living tissue while secreting fluids with antibiotic properties. Many patients with joint inflammation and diseases swear by "bee venom therapy," even though it may be relegated to the category of alternative medicine by the healthcare establishment. Spider, scorpion, and insect venoms continue to yield promising derivative compounds. Some fireflies produce chemicals that show promise in fighting herpes.

Paper wasp nest in Cape May, New JerseyArt, science, and inspiration

Many people find inspiration in the world of insects. We owe the invention of paper to ancient peoples in Asia who observed paper wasps constructing their nests of chewed wood and plant fibers. We continue to refine the performance of our aircraft thanks to experiments on, and observation of, insect flight. Insects are being enlisted in the fight against terrorism because of their acute chemo-tactile senses that far exceed our own abilities to detect harmful substances and agents; and their small size that allows them access to the most remote cracks, crevices, and other cavities. Artists are endlessly inspired by the beauty, colors, and patterns of insects.

Cochineal scale insects on cactus, ColoradoRaw Materials

Lastly, insects and their kin provide us with many invaluable raw materials and products. Silkworms and spiders produce silk with different properties of strength, durability, and elasticity, often exceeding the quality of synthetic fabrics. Honeybees produce honey, and beeswax. Cochineal scale insects produce organic scarlet dye, and the lac scale insect yields shellac. Many cultures also consider insects themselves as a staple food source, a practice known as "entomophagy" that is steadily gaining favor in modern western cultures.

Tiny gall wasp (Cynipidae) I found yesterday, ColoradoPersonally....

Personally, I value insects and arachnids as an endless source of fascination. Their physical diversity is mind-boggling. The behaviors they engage in are amazing. You can find them anywhere and everywhere, even inside your own home in the middle of a cold winter. Their stories demand telling, and I feel honored and privileged to have a modicum of ability to bring them to life for others.

What is it about "bugs" that you are thankful for? I encourage you to share your thoughts and feelings here.

Source: I wish to thank the Missoula Butterfly House and Insectarium for sharing the quote at the top of this post. Please visit their website, donate if you are able, and "like" them on Facebook. Thank you.

Ok, Save Some Bugs

A couple weeks ago I ran a post suggesting that efforts to save individual insects often is a waste of time, or at least was a misplaced investment of one's energies. Thanks to thoughtful and polite comments here and in social media, it is clear that some clarification is in order, and some exceptions, perhaps.

Go ahead and save the Monarchs....

I will stand by my assertion that rescuing individual insects is largely an ineffective strategy; but I would be a lot less animated about it were it not for this persistent notion that we can choose which species are worthy of salvation. That is not how Nature works. At the level of ecosystems and the biosphere, we have to save everybody (read "species") in order to save anybody. Recent news reports like this one in the New York Times, citing scientific studies, point to that very fact.

....but then save the Milkweed Bugs, too....

A perfect case making my point for the wrong way to act is the person who plants milkweed in their garden and then insists it be for "pollinators and Monarchs only." Therefore, competing milkweed bugs and milkweed beetles must be banished, killed on sight in fact. Really? Look at a wild stand of milkweed and you will see an entire ecosystem of pollinators, herbivores, predators, and parasites functioning exactly as they should, complementing each other's roles, with adequate survivorship of all parties. Listen, if you have a full complement of players in your yard's milkweed patch, then you are doing everything right! Relax. Neglect is often the best thing you can do once you get a native plant garden going.

....and also the Milkweed Beetles

We need more people to stand up for species that are "ugly," suffer from stereotypes and slander in the media, or languish in obscurity. It is those behind-the-scenes species that are doing the real work of keeping the biosphere spinning. Were it not for dung beetles and termites, we would already be buried by debris and animal waste at a scale that bacteria could not begin to attack. The processes of decay would be halted.

Dung beetles are a vital natural clean-up crew

Insects are the foundation of the food web, without which all other organisms would perish in a domino effect. If you like to fish, then you need aquatic insects. If you are a birder, you can thank virtually all insects for feeding our fine feathered friends.

The point is that all organisms have value, though it may not be obvious, or directly relevant to your everyday life. Our own species has been shaped over the eons by our interactions with other forms of life, and that will always be the case. It can continue to be a positive thing, if we keep all the pieces, or an apocalyptic disaster if we continue in our hubris as a species that we know best how to manage the wild world.

Grasshoppers and other insects feed the birds!

Even if you only value organisms for what they can do for us, nobody knows if the next miracle medicine could come from some beast we currently loathe. Increasingly, bioprospecting for pharmaceuticals has revealed just how rich the insect world is in chemical compounds that might one day cure our worst ills. We do not know what potential we are losing when we pave over, plow under, and deforest natural ecosystems.

You want to save something, hands on? Volunteer for your state or local wildlife agencies, zoos, and other institutions that are trying to resurrect truly endangered species like the American Burying Beetle, Salt Creek Tiger Beetle, Karner Blue butterfly, and other imperiled species you probably have never heard of. Their populations are at such a low level that saving individual specimens really is critical.

Even yellowjackets are valuable pollinators, and predators of pests

The late, great entomologist Howard Evans wrote in his classic book Life on a Little Known Planet: "I happen to like yellowjackets; do I not have a right to yellowjackets if my neighbor has a right to a cat?" He continues "If freedom means anything at all, it means the right to choose one's environment and one's friends." Ladies and gentlemen, I urge you to choose wisely.

Another Viral Moth Video....

In service to my colleagues who have waning patience as they are bombarded with the latest social media sensation, I offer this explanation to the moth with the "tentacles" coming out of its posterior. Here is the circulating image, but there is also a video that is associated with most Facebook posts.

© "Gandik" via Facebook

Ok, first things first. This moth is Creatonotos gangis, an arctiine (tiger) moth from southeast Asia and Australia. The specimen shown is a male. He is everting his androconial glands or coremata (Greek for "feather duster"). The glands are normally concealed within his body, and are inflated at will by air pressure or blood pressure. Less dramatic versions of these organs are known as "hair pencils." Usually concealed within his abdomen, the coremata are deployed when he is seeking acceptance by a mate.

Male pyralid moth deploying his "hair pencils" © Nicky Bay

Wait, you thought female insects were the ones using pheromones (scents used mostly to attract the opposite gender, but with other functions, too, especially in social insects)? Well, me, too, so I did a little digging. Turns out that the male's sexual chemicals are not meant for long-distance attraction of females, but to communicate his "fitness" as a mate. So, the products of androconial glands have been likened to aphrodisiacs, tranquilizers, or narcotics, aimed at seducing the female. Ok, but how? It is a long story....

© David Rentz via Joanie Mars on Facebook

As caterpillars, many tiger moths (subfamily Arctiinae of the owlet moth family Erebidae) feed on toxic plants. Milkweed is a good example. The plant is packed full of cardiac glycosides, potent poisons intended to discourage herbivores, including caterpillars, from consuming it. Not only are some caterpillars able to overcome the toxicity, they incorporate it into their own bodies to make themselves toxic to their predators. This is called sequestering, and the commandeered poison stays with the insect throughout metamorphosis and into adulthood. One of the byproducts in male moths is the pheromone emanating from those androconial glands. He thus demonstrates to the female that he is genetically superior based on a greater quantity of accumulated toxins that she can then pass on to her offspring.

Our common U.S. Acrea Moth everting his glands © Rosella Flores

This is a relatively dry explanation of these remarkable structures in male tiger moths. You owe it to yourself to be better entertained and further enlightened by an article in Wired magazine by my good friend and colleague Gwen Pearson. Even the graphics are better, and a GIF has never been funnier, at least in the context of entomology.

Close-up of male Acrea Moth glands © openi.nlm.nih.gov

So, far from "terrifying" as a similar viral graphic was labeled in a headline from Huffpost, these glands are an amazing example of evolution, just like elk antlers and other male adornments. Please share the fascination, without the sensationalism. Thank you.

Are We Saving Species by Rescuing One Individual Bug?

NOTE: I had to change the original title of this post because, believe it or not, it is a trademarked phrase! The owner of said patent/copyright informed me of this on September 17, 2019 and asked that I remove the title.

Increasingly, thanks to social media, I am struck by how many people attempt to save individual insects they find injured or lethargic. On one hand this empathy for other life forms is encouraging, but on the other hand the energy investment is grossly misplaced.

© Youtube.com

The problem is that the media has painted honey bees and Monarch butterflies in particular as highly vulnerable if not on the brink of extinction. The implied message is that every individual of these species needs protection in every way possible! Consequently, people spend more time "rescuing" individual specimens than in protecting or creating habitat, working to curb pesticide use in their community, or engaging in other strategies that would have a far greater impact on improving the health of the entire species.

Another problem is that most people are not knowledgeable enough to recognize when a given insect really is in trouble. The wrong assessment happens over and over with bees in particular. Bees often become inactive when it gets too cold for them. They rest on whatever object is available and often this is a more conspicuous spot than normal. A good Samaritan human believes the insect is in peril and needs the equivalent of a sugar-water IV, stat! No, it does not.

Further, in late summer and fall, chances are you are saving a male bee, which is even less useful. Male bees live a short life in which their only purpose is to mate with a female. They do not possess pollen baskets, so are less effective pollinators than female bees.

Another aspect of life that we forget is that insects, like any organism, are prone to developmental problems that cannot be overcome. Improper emergence from a chrysalis will leave a butterfly crippled beyond repair. It happens. Insects reproduce in large numbers to overcome those deficits. Insects are incredibly durable once they mature, and losing half a wing barely slows down a butterfly or a bee. We should be in awe as much, if not more, than in sympathy, let alone pity.

Ok, so last month my wife and I were on vacation in Cape May, New Jersey, and we happened upon a Monarch trapped in a spider web. We intervened. It was a quick fix, simply disentangling the insect and sending it on its way. The whole investment was maybe forty seconds. We understood the insect could collide with a vehicle later that same day. Our expectations for the survival of individual insects are low, given our knowledge of their biology.

Contrast that example with an online video that shows how to mend a broken wing on a Monarch. More than a few such organizations have exploited the "sky is falling" scenarios centered on the Monarch, and one has to question the motives of some of them. Yes, older, established conservation organizations use overly alarming narratives, too, but the best ones measure their tone and can point to historic successes in legislation and habitat protection.

You want to curb insect mortality? Then give up driving. For every insect you nurse back to health, you kill dozens, if not hundreds in the course of operating your motor vehicle. Even bicyclists take their toll. I have seen countless insects mortally wounded, or crushed, on bike paths.

Basically, insects are better served by actions aimed at enhancing habitat health, and planting native vegetation in the landscape of your own property where you are able. Tear out the lawn, or most of it, and do your best to mimic the natural ecosystem where you live. Want to go a step farther? Start a dialogue with city and county officials to restructure weed ordinances and other codes that currently restrict the ability of homeowners to plant for wildlife. Educate your homeowners association to make those communities more wildlife-friendly without compromising safety and property values.

Also, stop insisting that one species is somehow more worthy of our attention than any other. Stop categorizing insects as "friend" or "foe." Such distinctions do not apply to the overwhelming majority of life on this planet.

Be proud of yourself for having empathy for other living things; but, channel that into something that will make a difference beyond the individual insect or arachnid. Do intervene for birds, mammals, reptiles, and amphibians, all of which have far longer lifespans than invertebrates, but make sure you do it legally and correctly. Carry on.

The Wasp Wall

South Cape May Meadows in Cape May, New Jersey is a property managed by The Nature Conservancy (TNC) for birds and other wildlife. Near the parking lot stands a shed that itself is something of a refuge for a whole community of insects. One wall, facing west and with beams that make something of an overhang or trellis, is being worked over by the Eastern Carpenter Bee, Xylocopa virginica. The abandoned nests of these solitary bees are then used by mason wasps, leafcutter bees, and other solitary Hymenoptera.

The shed at South Cape May Meadows, behind the arbor entrance

During our visit this past September 24, we noticed the holes, then soon saw females of the Four-toothed Mason Wasp, Monobia quadridens, exploring some of those cavities. I wrote about this species previously, detailing its life cycle, but this was the first time I had observed them coming and going from nests.

Female Monobia quadridens entering her nest

One female delivered a paralyzed caterpillar during our observations. It was a surprisingly small larva given the size of the wasp, but then she caches several victims in each cell before laying a single egg, putting up a partition of mud, and then starting a new cell along the length of the tunnel inside the wood.

Female cuckoo wasp, Chrysis sp., prospecting for a host

One might think that nests in such solid material would be impermeable to parasites, but not so. We watched a brilliant blue-green cuckoo wasp, Chrysis sp., investigate some of the holes for occupants. Given a nest in progress, she would infiltrate and lay her own egg inside. Her larva would then consume the prey items left by the rightful owner for its offspring. Cuckoo wasps are nearly impregnable, with a very dense exoskeleton that deflects the bites and stings of host wasps. Cuckoo wasps can roll into a ball to further protect themselves.

Female Leucospis affinis ovipositing in a host nest

A less common parasitic wasp also came to the wall. Leucospis affinis is a large chalcidoid wasp. The female is easily recognized by the whip-like ovipositor that curls over the top of her abdomen. The ovipositor is the organ she uses to lay her eggs....by drilling through the solid wood directly into one of the cells of her host. How she divines the location of a host larva through a layer of dense cellulose is a mystery to me, but her aim is usually true.

Nest closure of mason wasp or carpenter bee

A completed nest of a mason wasp is usually identified by the mud plug that closes the entrance to the hole in the wall. Because the soil at Cape May is essentially all sand, it was difficult to tell if we were looking at a sand closure or a sawdust closure that would be the work of one of the carpenter bees.

Nest closure of leafcutter bee, Megachile sp.

Easier to identify was the completed nest of a leafcutter bee, genus Megachile. Leafcutter bees snip oval pieces from leaves of living plants and fashion those clippings into barrel-shaped cells that they stack along the length of a tunnel in wood, or underground in the case of a few species. The female bee then cuts at least one perfectly circular leaf fragment that serves as a "lid" for the completed cell.

Nest of grass-carrier wasp, Isodontia sp.

We found one hole filled loosely with bits of grass, and we surmise this was the work of yet another kind of wasp, the grass-carrier. These solitary wasps, related to mud daubers in the family Sphecidae, use dry grass to fill, and/or partition, and plug their nest tunnels. Near Cape May Point State Park we did witness a female Isodontia mexicana select and bite off a dry grass stem to take back to her nest, so we know these insects were active.

Female grass-carrier wasp, Isodontia mexicana, cutting a piece of grass

Ironically, one other kind of wasp was tearing the wall down one mouthful at a time. Workers of the Bald-faced Hornet, Dolichovespula maculata, would alight on the wall and begin chewing off wood fibers to mix with their own saliva. This creates a pulp that they use to make durable paper nests. Looking more closely at the wall we realized that the scores of yellow streaks on the otherwise weathered gray wooden surface were where yellowjackets (of which the Bald-faced "Hornet" is just another species) had stripped fibers for use in building their nests.

Bald-faced Hornet gathering wood fibers to make paper

No doubt, earlier in the season there would be even more activity around this wall. The shed is still standing, sturdy as ever, so the insects are not doing much, if any, structural damage. Please consider that if you find that your own shed is becoming home to carpenter bees and other insects. You may find yourself as enthralled as we were by the little ecosystem started by carpenter bees.

Female Monobia quadridens exiting her nest

Sources: Evans, Howard E. 1963. Wasp Farm. Ithaca, NY: Comstock Publishing Associates (Cornell University Press). 178 pp.
Buck, Matthias, Stephen A. Marshall, and David K.B. Cheung. 2008. “Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region,” Canadian Journal of Arthropod Identification No. 5: 492 pp. (PDF version).
Krombein, Karl V. 1967. Trap-nesting Wasps and Bees: Life Histories, Nests, and Associates. Washington, DC: Smithsonian Press. 570 pp.
Krombein, Karl V., et al. 1979. Catalog of Hymenoptera in America North of Mexico Vol.2 Apocrita (Aculeata). Washington, DC: Smithsonian Institution Press. Pp. 1199-2209.

"Arach" is Back!

One of the things I look forward to each autumn is the annual Flickr event known as "Arachtober". It is a Flickr group which slumbers between November and the following September, but remains a tradition among arachnophiles and macro photographers. There are always mesmerizing images posted from all corners of the globe.

Marbled Orbweaver, Kansas

Arachtober manages to recruit several new participants each year through word of mouth, blogs, and sheer curiosity. Not only spiders, but scorpions, ticks, mites, harvestmen, and all other arachnids are eligible for inclusion. Don't forget the artistry of spider webs, too, whether dew-adorned or dry.

Apache Jumping Spider male, Colorado

The only hard and fast rule of Arachtober is that the images you post to the group must not have appeared on your own Flickr photostream previously. Allowed quantity of images per day varies at the discretion of the group administrator.

Banded Garden Spider female, Colorado

Overall, interest in spiders seems to be increasing among the general public, and arachnids are achieving a much higher profile than ever before. This is great news, for there is still a great deal of work to be done to combat myth, superstition, misinformation, and fear.

Wolf spider, Alopecosa sp., Colorado

Please consider contributing to "Arachtober" on Flickr, or find another way to dedicate some time to sharing your spider observations, questions, or images. There are many groups on Facebook devoted to spiders and their identification, for example; and presumably, the same applies to Instagram. There is much you can contribute to our collective knowledge by doing so. Thank you.

Grasshopper or Locust?

A person on a Facebook insect identification group recently asked a very good question about the difference between a grasshopper and a locust. You would think it is pretty straightforward, but not so fast.

The American Bird Grasshopper, Schistocerca americana, is related to some grasshopper species in Europe and Africa that can become locusts; and it sometimes migrates beyond its usual geographic range in the U.S.

Most of us think of locusts in the context of Biblical plagues in Africa and parts of Europe, in ancient times. Such plagues still happen, and they are almost apocalyptic in their destructiveness. They even occur in North America on occasion, as well as other parts of the world, so there must be more than one species of locust, right? Yes, and no.

Two-striped Grasshopper, Melanoplus bivittatus, has been overwhelmingly abundant in recent years along the Colorado Front Range

Locusts are not a species of grasshopper, they are the result of overcrowding in the nymph stage of many kinds of grasshoppers. Under favorable conditions, there is an extraordinary survival rate of young grasshoppers, which are called nymphs. When they are literally so abundant and concentrated that they are rubbing elbows (well, "knees" is probably a more appropriate term), this friction causes them to detour from their normal route of metamorphosis.

Instead of maturing into the usual grasshopper, the adult stage features longer wings and other body modifications that permit them to fly greater distances, remain airborne for longer periods, and to undertake these migrations from one food source to the next over long distances. They also may be aided by winds ahead of storm fronts.

The Clear-winged Grasshopper, Camnula pellucida, is prone to population outbreaks in the American West

This is something of a simplification of the physiology of locusts versus normal grasshoppers, but a surprising number of species have the potential to morph into locusts when conditions are right. Then they overwhelm the landscape, defoliating every plant in their path.

Locust swarms will devour plants they would not normally eat. I recall a presentation about a locust epidemic in Oregon where the scientist showed slides of juniper trees (yes, juniper trees) that had been reduced to skeletons by grasshopper swarms. The locusts have even been known to eat garments on clotheslines. Grasshoppers are also omnivores, and will not hesitate to eat dead members of their own species, or gnaw on injured or even healthy ones. It is late in grasshopper season here now in Colorado, and I regularly see grasshoppers with wings reduced to stubs thanks to hungry comrades.

A victim of the grasshopper-killing fungus Entomophaga grylli

Fortunately, for us at least, grasshoppers face many mortality factors. While it has been a banner year for grasshoppers this year along the Colorado Front Range, huge numbers have succumbed to the entomopathic fungus Entomophaga grylli. The insidious fungus grows inside the insect, eventually commandeering its brain and forcing it to behave abnormally. The grasshopper, through no will of its own, climbs to the top of a tall weed, assumes a death grip embracing the stem, and dies. The fungal spores then erupt and rain down on healthy grasshoppers below to begin the cycle again. The spores may even decapitate the dead grasshopper as they exit.

Grasshoppers are the chief grazers of the prairie, even more impactful than livestock, deer, pronghorn, elk, and bison. Natural rangeland can usually withstand their feeding, but ranchers obviously see them as competition and exercise chemical controls when necessary. Since grasshoppers are mostly generalist feeders (a few specialize on only certain broadleaved plants), they pose a threat to agricultural crops, too.

A specimen of the extinct Rocky Mountain Locust
© Bugguide.net

Ironically, the Rocky Mountain Locust, Melanoplus spretus, once the most abundant and devastaging insect pests ever to occur in North America, is now extinct. The book Locust, by Jeffrey A. Lockwood, chronicles the rise and dramatic fall of the species, which ultimately vanished from the U.S. landscape by the early 1900s. I will not spoil the solving of the mystery, as Lockwood's account is far more riveting than anything I could craft if I was even prone to writing historical fiction. Let us just say it is a cautionary tale.

Historical range of the Rocky Mountain Locust

We can certainly be grateful that we seldom experience such traumatic explosions of grasshoppers here on American soil, but we should be empathetic to other nations that do. Entire economies can be on the verge of collapse in the wake of such devastation.

Source: Lockwood, Jeffrey A. 2004. Locust. New York: Basic Books (A member of the Perseus Books Group). 294 pp.