Wake-up call for boxelder bugs: Boisea trivittatus

 

Warm weather puts boxelder bugs on the move. You may see one or buckets of boxelder bugs outside your home in coming weeks. Image credit: Margi Raupp

 

Hordes of boxelder bugs gather on the outside of a home to enjoy a day in the sun – the perfect Spring Break for a boxelder bug! Bet you’re glad this isn’t your house!

Two weeks ago, we met a pesky home invader, the brown marmorated stink bug, as it stirred from its indoor redoubt and annoyed inhabitants of a home while attempting to escape outdoors to the natural world. As temperatures once again soared into the 70s, we turn our attention to reports of hordes of another rascal, boxelder bugs, festooning a suburban home. Boxelder bugs are members of the order Hemiptera, a.k.a. the “true bug” clan, characterized by their sucking mouthparts and gradual metamorphosis. Two years ago, a bug-friendly neighbor inquired about vast numbers of boxelder bugs aggregating on their patio and the sunny side of their house. As our friends opened and closed doors, these rascals snuck inside for reasons known only to themselves and Mother Nature. Last week, a family member in eastern Pennsylvania sent images of dozens of boxelder bugs lounging on the side of their house. How did these rascals arrive and why are they now active?

Ok, boxelder bugs are a little creepy when you see hordes of them on the side of the house or the tool shed. (private)

When not feeding on seeds, boxelder bugs will dine on bird poop. Yum!

Here’s the story. Depending on geographic location, boxelder bugs complete one to three generations each year. They survive winter’s ravages hiding in cracks and crevices beneath shutters and under siding, and by entering other access points in structures. In natural settings outdoors, winter refuges include loose bark or hollows of trees, tangles of brush, and voids under rocks. During the last few weeks as temperatures soared into the upper 60s and 70s here in the Washington metropolitan region, boxelder bugs emerged from these redoubts and made their presence known inside homes as they sought a way out. On the exterior of homes, they aggregated in large numbers to soak up thermal energy from the sun. Spring and summer are times for foraging on a wide variety of plants, including seeds of their namesake tree, boxelder, as well as other members of the maple clan. Both adults and nymphs feed on propagules of many different kinds of seed-bearing trees and on the juicy tissues of many other landscape plants.

Seeds from this old maple tree support a population of boxelder bugs that sun themselves on the side of a home on warm spring days. Wanderers sometimes enter homes, creating a nuisance. Others battle as they feed on a maple seed on the ground. Males and females pair off, and after mating females deposit eggs in many places, including sides of buildings. Wingless nymphs that hatch from eggs feed on a wide variety of plants.

Female boxelder bugs deposit eggs in clusters. Tiny nymphs will hatch and move to the ground to consume seeds and other plant tissues.

After gaining sufficient nutrients, mated females deposit eggs on a wide variety of substrates on the ground and also on human-made structures. In autumn, large clusters of boxelder bugs gather on trees and buildings where they become a nuisance. In the waning days of autumn, they seek winter shelter. They enter homes through cracks in the foundation, gaps in siding around windows or vents, and beneath doors and windows. On cold winter days they are inactive, but as winter retreats and temperatures warm, restless boxelder bugs move about and make their presence known inside and out.

Boxelder bug nymphs are wingless nymphs.

Boxelder bugs are not harmful to humans or pets. They do not bite, sting, or reproduce indoors, however, if you squash them on your drapes or walls, they will stain. So, don’t do that.

To limit the number of boxelder bugs taking up residence in your residence, eliminate overwintering places such as piles of lumber, fallen branches, or other refuges close to the house. Some folks go as far as removing boxelders, other maples, and ash trees from their landscapes to reduce food sources for nymphs and adults. Weatherproofing your home can also help keep these invaders out. Caulk and seal openings where utilities enter the home. Repair or replace door sweeps and seal any openings around windows, doors, or window air conditioners.

If you find them inside your home, you might try this. Simply get out the hand-held vacuum, suck them up, and release them back into the wild. It is wise to choose a liberation point some distance away from your home.

The boxelder bug’s clever mouthparts (proboscis) enable it to feed on seed and plant tissues.

Acknowledgements

We thank Margi, George, Anne Marie, and Dennis for sharing their boxelder bugs, and providing inspiration for this episode of Bug of the Week. The wonderful reference “Urban Insects and Arachnids: A Handbook of Urban Entomology” by William Robinson was used as a reference.

Spring arrives and with it, delightful Plasterer bees: Colletes spp.

 

From the safety of its burrow, a plasterer bee takes a peek at a bug geek with a camera. How cute is that?

 

We visited plasterer bees in the spring of 2020 at the onset of the Covid epidemic. Let’s go back in time to that earlier episode and see how these spring beauties roll.   

Soil conditions in this lawn support nesting sites for thousands of plasterer bees. Credit: Marlene Stamm

April 13, 2020 - “Fortunately, before the shelter-at-home orders kicked into high gear, I was able to visit a park and vacant golf course to piece together more details about these fascinating ground-dwelling bees known as plasterer bees. Along with beetles, flies, and butterflies, bees are among the premier pollinators on the planet. Plasterer bees are some of the very first native pollinators to appear each spring. The name plasterer stems from their intriguing behavior of building galleries in the ground and then coating the interior surface of their burrow with a thin, glossy, translucent material produced by a gland in their abdomen. Plasterer bees use their tiny mouthparts to remove the soil when constructing their galleries. The excavation is accompanied by a buzzing sound that may help loosen particles of soil and aid in the digging process. The bee’s mouthparts are also used like a mason’s trowel to spread the glandular secretion on the inside of the burrow before it dries into a cellophane-like coating. How clever! This habit of sealing their galleries gives this bee the common name plasterer bee.

What’s up with all these holes in the ground? Watch, listen, and learn a little bit about the fascinating lives of plasterer bees.

Plasterer bees are relatives of honey bees and bumble bees but, unlike their cousins, these bees are solitary. Rather than living in a communal nest, each female plasterer bee constructs a subterranean gallery of her own to serve as a home for her brood. Burrows are provisioned with a semi-liquid concoction of nectar and pollen from flowering plants that bloom early in the spring. This yummy delight is food for bee larvae that develop during the summer and fall within the galleries. Although they are not considered social insects, large numbers of plasterer bee galleries are often abundant in close proximity in sandy soils with thin vegetation.”  

Thin grass, a sunny hillside, and sandy soil provide nice conditions for plasterer bees in my backyard.

While exploring nesting sites along Disc Golf Course in Patapsco State Park last week, I was delighted to see dozens of small plasterer bees zooming inches above the ground. While swarming bees at the margin of fairways might dismay some disc golfers, bee dread is unwarranted. Unlike yellow jackets, baldfaced hornets, and other stinging terrors, plasterer bees are docile and extremely reluctant to sting. Remember, each female bee is a mother and to risk her life by stinging a human could mean instant curtailment of her reproductive potential should she die in the encounter. Over large areas of a balding zone in the rough, several burrows could be found in each square meter of ground. The plasterer bees were not responsible for the balding turf. They simply colonize areas where the turf is naturally thin. If you see swarms of small hairy or metallic colored bees constructing burrows or emerging from galleries in your garden or lawn, please resist the urge to treat them with insecticides. Several species of native pollinators, including anthophorid bees, yellow-faced bees, andrenid bees, halictid bees, as well as plasterer bees nest in the ground. Enjoy these beauties and give them a break. They pollinate plants and keep our planet humming.  

On a warm afternoon last week plasterer bees swarmed over the surface of a sun-drenched embankment along the Patuxent River. Excavations by hundreds of plasterer bees created tiny volcanoes of brick red soil along the slope. While some bees buzzed about, others were busy constructing burrows or dashing off to bring provisions back to their subterranean galleries.

Acknowledgements

Bug of the Week thanks native bee guru Sam Droege for helping to identify bees seen in this episode. We also thank Marlene for sharing an image of her bee-friendly yard, providing both a home for these fantastic native pollinators and the inspiration for this story. The wonderful article “Ecology, Behavior, Pheromones, Parasites and Management of the Sympatric Vernal Bees Colletes inaequalis, C. thoracicus and C. validus by S. W. T. Batra was used as a reference.

Reveille for BMSB: Wake-up call for brown marmorated stink bug (BMSB), Halyomorpha halys

 

One morning I discovered a stink bug waiting on my travel mug for some morning joe.

 

With our planet reaching the unenviable landmark of experiencing the warmest February on record and the warmest 12-month period in history, March temperatures keep marching right along with more projected highs near 70. As predicted, record warmth in temperate zones like the DMV means that insect activity will begin earlier and extend later each year than it has in years past. Not only will the action start earlier outdoors, but insects that have overwintered in our homes will be on the move earlier as refuges in attics and various nooks and crannies around our homes heat up. With temperatures now in the mid to upper 60s, home invaders like stink bugs are on the move in homes and offices, accumulating on windowsills, walls, and doors and buzzing about indoor lights at night. Why all the activity at this time of year?

In autumn stink bugs seek shelter in attics, beneath siding, and behind shutters.

The answer lies in the age-old pattern of life crafted by stink bugs to survive the ravages of winter and emerge just in time to take advantage of bountiful leaves and fruit found on plants in the spring. Millions of folks throughout the nation were treated to invasions of stink bugs last autumn as the horde sought refuge in homes, schools, and office buildings. Many people mistakenly believe that stink bugs enter buildings in winter to ‘get warm’, but this is not the case. In the natural realm where stink bugs evolved over millions of years, stink bugs sought winter refuge in sheltered spots beneath the bark of trees or in rocky crags. Protected from the onslaught of winter, stink bugs chilled out and entered a season of inactivity akin to hibernation where they awaited the return of favorable temperatures and springtime food. Lengthening days and warming temperatures signaled the return of leaves, flowers, and fruit. With the return of food sources, stink bugs answered Mother Nature’s wake-up call and moved from their refuges to the greening landscape. During the past week with warm weather, flowers, leaves, and yes, pollen, exploded on trees, shrubs, and herbaceous plants in the Washington metropolitan region. Inside attics or beneath the siding on homes, these warm days have convinced stink bugs that spring has arrived and that it is time to return to the wild to seek food and pursue the biological imperative of finding mates and laying eggs. On warmish days this winter, every now and then I collected a stink bug or two wandering about the kitchen or living room. But as of this week, these occasional sightings have turned into a steady stream and I collect stinkers daily.

As you deal with stink bugs this spring, here are some things to consider. Recently, I was asked if “stink bugs breed in my home?” To the best of our knowledge, the answer to this question is no. In the normal course of events, stink bugs move from winter refuges to plants outdoors where they feed for several weeks before they become competent to lay eggs. In your attic or an unused bedroom there is simply no food to provide the sustenance needed by stink bugs to produce eggs. Even if a stink bug laid eggs indoors on a windowsill or wall, there would be nothing to sustain the young bugs, which require plant food for growth and development. Having made this claim, I might back-peddle just a little, as we have received reports of stink bugs feeding on house plants such as orchids and potted ponytail palms. Will stink bugs lay eggs on houseplants indoors? One homeowner discovered a batch of stink bug eggs on a houseplant in the spring a few years ago. So, the final answer to this jeopardy question is yes, they might breed in your home. The chances of stink bugs sustaining a population in your home probably lies somewhere between zero and nil, unless you have bountiful fruit bearing plants in your home and do everything to ignore stink bugs dashing about on those plants.

Another question that always comes up is “what should I do about stink bugs that appear in my home this spring?” Sweeping, vacuuming, or simply picking them up and disposing of them is still our recommendation for control indoors. Because they will be active for a relatively long period of time, we are not recommending the application of insecticides to indoor living spaces to control stink bugs as they appear. Exposure of children and pets to pesticides could be worse than exposure of children and pets to stink bugs. In fact, many pets and some children will be amused by a few stink bugs wandering about.

As daytime temperatures warm in spring, stink bugs that invade homes in autumn try to escape to the world outdoors. Whether they are meandering across a mantle, grooming on a coffee mug, dashing up a storm door, or visiting the beach on a screen saver, stink bugs are on the move.

Window sills collect stink bugs on warm days in late winter and spring as they attempt to exit homes.

Will stink bugs be as problematic this year as they were in the watershed years of 2010 and 2012? Probably not. Although stink bugs have now spread to 47 states and 4 Canadian provinces, in our region most people agree that fewer stink bugs plagued gardens, homes, and farms recently than they did several years ago. Fascinating studies suggest that a combination of climatic events and Mother Nature’s Hit Squad of predators, parasitoids, parasites, and pathogens have conspired to smack down populations of stink bugs. Scientists at Virginia Tech found that rapidly plunging temperatures associated with weather phenomena such as the polar vortex may reduce survival of overwintering stink bugs. Studies conducted at the University of Maryland revealed that young stink bugs thrive only when the proper complement of microbes are present in their gut. These microbes pass from mother to offspring when youngsters consume exudates smeared on the surface of their eggs by their mother. Without this complement of microbes, survival and development of stink bugs is reduced. Authors suggest that high temperatures may harm this microbiome and thereby reduce colonization by stink bugs. Maybe our record warmth does some good after all.

With respect to Mother Nature’s Hit Squad, in previous episodes of Bug of the Week, we met vicious predators such as the Chinese Mantis, Wheel Bug, and Black and Yellow Garden Spider as these feasted on stink bugs. Scientists at the USDA found several species of indigenous predators such as ground beetles and katydids attacking eggs of stink bugs in orchards and vegetable crops. Researchers at the University of Maryland discovered several species of tiny native wasps metering out significant mortality on eggs of stink bugs in ornamental plant nurseries. And yes, stink bugs are susceptible to pathogens as well. Scientists at Cornell have described a tiny microsporidian parasite called Nosema maddoxi infecting several populations of stink bugs around the nation. Collectively, weather events and natural enemies are helping humans to win the war on one of the most serious recent invaders to arrive in our country.

Acknowledgements

To learn more about the brown marmorated stink bug, please visit the following website: http://www.stopbmsb.org/  

 To learn what to do when stink bugs get inside, and how to keep them out, watch the following video: https://youtu.be/0kG-2fetbZA

The following articles were used to prepare this episode: “Cold Tolerance of Halyomorpha halys (Hemiptera:Pentatomidae) Across Geographic and Temporal Scales” by Theresa M. Cira, Robert C. Venette, John Aigner, Thomas Kuhar, Donald E. Mullins, Sandra E. Gabbert, and W. D. Hutchison. “The Importance of Gut Symbionts in the Development of the Brown Marmorated Stink Bug, Halyomorpha halys (Sta˚l)” by Christopher M. Taylor, Peter L. Coffey, Bridget D. DeLay, and Galen P. Dively. “Frequency, efficiency, and physical characteristics of predation by generalist predators of brown marmorated stink bug (Hemiptera: Pentatomidae) eggs” by William R. Morrison III, Clarissa R. Mathews, and Tracy C. Leskey. “Field surveys of egg mortality and indigenous egg parasitoids of the brown marmorated stink bug, Halyomorpha halys, in ornamental nurseries in the mid-Atlantic region of the USA by Ashley L. Jones, David E. Jennings, Cerruti R. R. Hooks, and Paula M. Shrewsbury. “Nosema maddoxi sp. nov. (Microsporidia, Nosematidae), a Widespread Pathogen of the Green Stink Bug Chinavia hilaris (Say) and the Brown Marmorated Stink Bug Halyomorpha halys (Stål)” by Ann E. Hajek, Leellen F. Solter, Joseph V. Maddox, Wei‐Fone Huang, Alden S. Estep, Grzegorz Krawczyk, Donald C. Weber, Kim A. Hoelmer, Neil D. Sanscrainte, and James J. Becnel.

Beautiful butterflies pumping water: Daggerwings, Marpesia spp., and a pierid butterfly, Cepora spp.

 

A beautiful Cepora butterfly rests on a stone along a riverbank where other pierids gather to gain nutrients from alluvial soils.

 

As our lingering El Niño keeps local bugs in suspended animation, Bug of the Week makes a stop in Costa Rica before returning to Borneo where we recently visited scary potter wasps, stridulating longhorn beetles, fierce arboreal and terrestrial ants, stingless bees, giant millipedes, and pretty lanternflies.  This week we meet beautiful Marpesia butterflies on a Pacific beach and pretty Cepora butterflies along a riverbank in Gunung Mulu National Park. These gorgeous butterflies engaged in a poorly understood behavior called “pumping.” No, this is not the kind of pumping Arnold Schwarzenegger or Hans and Franz of SNL made famous with heavy weights and muscular contortions. In previous episodes we met temperate swallowtail butterflies feeding on unusual substrates including carcasses of fish and piles of dung to obtain vital minerals and nutrients not found in nectar of more traditional hosts like the blossoms of flowers.

Marpesia are famous for their glorious colors and wing patterns.

Butterflies frequently “puddle” in muddy soil using their proboscis to gather dissolved elements from moist mineral laden earth. “Pumping” is different. This infrequently observed behavior occurs when a butterfly rapidly imbibes water with its soda-straw-like mouthparts and rapidly expels it from the rear end. In 1963 Walfried Reinthal made the following observations of a swallowtail butterfly pumping at the edge of a swimming pool: “This pumping in of the water through the proboscis and at the same time eliminating it from intestines went on uninterruptedly for about the next twenty minutes. During this interim over two hundred and fifty drops of water were counted …” At a loss to fully explain this behavior Reinthal suggested that perhaps “the insect had to give itself a sort of internal lavage...”  Other observations of pumping include those of Eduardo Welling who witnessed a swarm of about 30 swallowtail butterflies pumping in a “stinking hollow of mud” near a lagoon in Quintana Roo. He wondered if the behavior was related to the excessive heat and humidity of the tropical day.

Watch as a lovely Marpesia sips water from the sand and expels droplets from its abdomen about once every five seconds. An equally lovely Cepora drinks along a rainforest riverbank and shoots water out its derrière. This poorly understood behavior in butterflies is called pumping.  

Butterflies have many mechanisms to warm and cool themselves, the business of thermoregulation. Basking in the sun, avoiding conductive heat loss in the wind, and shivering are all used by butterflies to warm themselves. Respiratory cooling by evaporation and shade seeking are mechanisms used by butterflies to chill out on a hot day. In his treatise on thermoregulation in butterflies, Harry Clench suggested that pumping might be a way for a butterfly to rapidly warm or cool itself depending on the differential between ambient air temperature and the temperature of the water being pumped from the soil. Although I find the notion of butterflies performing self-lavage odd and intriguing, hey, in the world of insects stranger things have happened. Watching beautiful Marpesia and Cepora expelling droplets of water is a strange and intriguing site to behold irrespective of the reason.

Acknowledgements

Bug of the Week gives special thanks to Carlos and Lawrence and our friends Pat, Kristie, Bob, Dan, and Paula who inspired this episode. “Behavioral thermoregulation in butterflies” by Harry Clench, “About the “pumping action” of Papilio at water” by Walfried Reinthal, and “More observations of the “pumping” action of moths at water, with notes on observations in Quintana Roo” by Eduardo Welling were consulted in preparation of this episode.