From the mailbag - When spotted lanternflies arrive, do stinging insects follow? Eastern yellowjackets, Vespula maculifrons, and a few other friends

 

This pretty yellowjacket nest was found beneath a set of steps near a deck outdoors.

 

Last week we visited spotted lanternflies as they continued their march through the DMV and other states in the eastern half of the United States. These killers of grape vines are a major nuisance in residential and commercial landscapes by virtue of their creep-me-out vast numbers and the prodigious amounts of honeydew they excrete as they feed. Honeydew is the sticky sweet waste product squirted from the rear-end of the lanternfly as it sucks nutrient rich phloem sap from a plant. Honeydew rains down on objects below, fouling fruit, foliage, lawn furniture and slow-moving humans that linger too long beneath trees. This carbohydrate rich liquid provides a substrate for a fungus called sooty mold, a black cloak that coats and disfigures underlying objects. Although sooty mold is not pathogenic, it diminishes the plant’s ability to capture energy from sunlight thereby reducing photosynthesis and impairing growth. As we learned in a previous episode, lanternfly honeydew is a favored food source for many kinds of stinging insects including bees and wasps. Recently, a large landscape maintenance firm in the DMV made an unprecedented purchase of cans of wasp and hornet sprays at a local hardware store. When asked “why so many”, the landscaper replied something like “the landscaping crews are running into unreasonable numbers of yellowjackets and various wasps as they clean up landscapes.”

On tree of heaven coated with sugary honeydew excreted by lanternflies and cloaked in black sooty mold, yellowjackets, paper wasps, and hornets forage. Along the edge and within a forest conservation area loaded with tree of heaven, several eastern yellowjackets have set up shop. Lanternflies nearby provide a ready source of food. Work and studies within the site have become spicy this summer due to the presence of stinging insects. Could recent reports of elevated numbers of wasp nests be linked to increasing numbers of lanternflies in areas infested with this invader? Only Mother Nature and the wasps really know.

Unlike the nests of bees, the nests of yellowjackets contain no honey or pollen. Yellowjacket larvae eat meat and carbohydrate rich foods gathered by the workers. In this regard, yellowjackets are beneficial because they kill many caterpillars and beetles that are pests in our gardens. By late summer and early autumn, colonies may contain thousands of workers and are often about the size of a football. Under extraordinary circumstances, some nests may persist for more than one year and reach gigantic proportions. There are reports of monster yellowjacket nests in southern states reaching the size of a “Volkswagen Beetle”. Yikes! I sure wouldn’t want to bump into one of those with the lawn mower. Well, as summer wanes towards autumn, colonies of many social wasps including yellowjackets, bald-faced hornets, and paper wasps will operate at a fevered pitch as they try to feed massive numbers of brood in their nests. As we learned in previous episodes, nests are aggressively defended and intruders are attacked with extreme prejudice.

Lil’ Rover demonstrates what happens when you sit on a nest of yellowjackets, but don’t worry, Lil' Rover has thick fur and was not harmed in the making of this video.

The venom of yellowjackets and their kin has evolved to bring maximum pain to vertebrates like skunks that pillage their nests. Encounters with these fierce ladies confirm that their venom brings agony to humans as well. Yellowjackets are capable of multiple stings, but only to a limited extent. Contrary to common belief, they have small barbs on their stingers and some may lose their stingers after an attack. If you are stung, apply ice to the site of the sting to reduce some of the damage and pain. Sting relieving ointments and creams are available in pharmacies and sporting goods stores and may help reduce the pain and itching. If you know that you are allergic and are stung, seek medical attention immediately. If you are stung and experience symptoms such as shortness of breath, difficulty breathing or swallowing, hives on your body, disorientation, lightheadedness or other unusual symptoms, call 9-1-1 and seek medical attention immediately. Desensitization therapy has proven very helpful to many people with allergies to stings of bees and wasps.

In some locations infested with spotted lanternflies, yellowjackets have become huge problems.

At Bug of the Week’s five-acre SLF tracking site, prior to the arrival of SLF a single eastern yellowjacket nest was discovered in the ground in 2021. With the arrival of lanternflies at the site in 2022, two yellowjacket nests were discovered near groves of tree of heaven, and with thousands of lanternflies spewing honeydew in 2023, five colonies of eastern yellowjackets have been discovered at the site to date. Adding even more moments of shock and awe to work at our study site are bald-faced hornets, which constructed an additional nest in a pile of brush. It could be coincidental that both lanternflies and stinging wasps are on the uptick due to some other environmental circumstance rather than being linked. At this point in time, we simply do not know. If you encounter a yellowjacket or bald-faced hornet nest and the nest is unlikely to be encountered by humans or pets, you may simply leave it alone. As mentioned before, these wasps help reduce populations of pests. If the nest is in a place that threatens you, children, or pets, you may consider eliminating it. Commercial pest control operators can assist you in this. I have purchased aerosol sprays, applied them according to instructions on the label, usually at night or in the evening, and had excellent success. Please be careful around these fierce ladies or you might feel their wrath.

Acknowledgements

Bug of the Week thanks Dr. Nancy Breisch for sharing her expertise and knowledge about stinging insects. We thank bold landscape managers and arborists for providing inspiration for this episode and Randy Taylor for sharing his pretty yellowjacket nest with us.

Why am I seeing more spotted lanternflies? Lycorma delicatula

 

Get ready to spot spotted lanternflies as they aggregate on trees in your landscape.

 

This week we turn to the Bug of the Week mailbag to explore why some folks are seeing more spotted lanternflies (SLF) around their homes and in their landscapes.

Reason 1. Since first detected in the US almost a decade ago, SLF has made an astounding range expansion from their entry point in Berks County, Pennsylvania to Huntington County, Indiana more than 580 miles away. This feat was not accomplished on their own. SLF are believed to move only a matter of several miles by walking, hopping, and flying. Nope, these vagabonds are super stowaways and heinous hitch hikers, moving as eggs, nymphs, and adults on vehicles, lawn furniture, plants, and other natural and human-made objects. Here in the DMV and adjacent states like Delaware, Pennsylvania, and New Jersey, they made beachheads and rapidly colonized several counties. All counties in New Jersey and Delaware house breeding populations, with Maryland not far behind. Larger states like Pennsylvania and Virginia still have uninfested counties but one look at Figure 1 suggests that these states are trending toward full saturation. Bug of the Week’s outdoor SLF tracking site near Antietam Battlefield in Maryland discovered a couple dozen SLF adults in 2022. Last week hundreds of adults festooned branches and trunks of trees. Dramatic population explosions are underway in several landscapes in the DMV and in some 14 states in eastern North America with new detections of infestations being reported on a weekly basis. So yes, due to range expansion there are indeed more lanternflies to be seen today in the US than there were just a few years ago.

Fig. 1. This graph summarizes the rapid spread of spotted lanternflies in the DMV and neighboring states over a period of five years. Data summarized by Michael Raupp from New York State IPM Program.

Reason 2. The second and perhaps more salient reason why there seem to be more SLF has to do with their seasonal phenology, that is the regular progression of development, survival, and activity throughout the year. In a previous episode in early May, we met tiny SLF nymphs as they hatched from eggs that survived winter’s onslaughts. Shortly after hatch, active feeding stages of spotted lanternfly were at their peak. Since early May, local populations of SLF dramatically declined as lethal weather events like cold and rain, murderous predators like spiders, mantises, and assassin bugs, diseases caused by fungi, and pesticide applications have taken their toll. The illusion that there are now more SLF than there were a few months ago has two explanations. First and foremost is the fact that adult SLF are roughly 10 times larger in size than tiny hatchling nymphs. Bigger bugs are easier to see. Second, these adult rascals are on the move, taking wing and winding up on the side of a house, on a sidewalk, lawn chair, or favored tree. While young, SLF nymphs feed on a wide variety of trees, shrubs, and herbaceous plants, more than 70 species of host plants are known. Nymphs are widely distributed in the landscape. Adults are most frequently found on a smaller sample of trees with invasive tree of heaven high on the list, and maples, walnuts, and a few others also commonly mobbed. Highly mobile adults and hordes of sap-sucking adults create a mien of many more lanternflies.

As we enter the period of adult migration, feeding, honeydew production, grape vine ravaging, and general annoyance, people will be wondering what to do. One popular and highly touted tactic is to do a little tap dance on SLF adults stranded on sidewalks or on the ground. The logic here is that every other SLF killed will be one less to lay eggs. Oh, every other bug because only females lay eggs and the sex ratio is likely 50:50, get it? Unfortunately, in the early stages of the SLF invasion, some 1.5 million SLF were killed by noble volunteers in Berks and nearby counties, yet these scoundrels managed to spread to surrounding counties and states more than 500 miles away. The contribution of stomping and squishing to reductions in SLF populations remains a mystery. Nonetheless, as Sheryl Crow opined, “if it makes you happy, it can’t be that bad”, so squish away if it makes you happy.

In April and May when millions of spotted lanternflies hatched, this year’s crop of lanternflies was at its zenith. As tiny black and white nymphs dispersed, they fed on myriad herbaceous and woody plants. Their colors changed from black and white to red, black, and white as they developed. Their numbers dramatically declined as weather, beneficial insects and diseases, and human interventions took their toll. Although fewer survived, when large adults gather to feed on favored trees or land on humans and buildings, their presence will be observed by more people. Many will perish on sidewalks and roads beneath the tires of vehicles and feet of humans.

What’s the bright spot here? Well, my tree care guys, certified arborists near ground zero in Pennsylvania, report that SLF populations have declined noticeably since the early years of the invasion in the late 20-teens. How so? Well, the aforementioned push-back by Mother Nature’s hit squad of predators, parasitoids, and pathogens coupled with host plant removal and highly efficacious and well-timed insecticide applications all help mitigate problems created by SLF. Quarantines enacted by several states appear to be slowing the spread of SLF on a regional scale. Let’s hope that the combined efforts of Mother Nature and clever humans can help keep this nocent invader at bay.

Fig. 2. Compare the distribution of spotted lanternflies in the United States in November of 2019 to the following image of their distribution in June of 2023. Data from New York State IPM Program.

Fig. 3. Compare the distribution of spotted lanternflies in the United States in June of 2023 to the previous image of their distribution in November 2019. Data from New York State IPM Program.

Acknowledgements

Bug of the Week thanks members of the Penn-Dell and Mid-Atlantic chapters of the International Society of Arboriculture for providing the inspiration for this episode and Dr. Shrewsbury for spotting and wrangling spotted lanternflies. We acknowledge the great work of scientists contributing to our knowledge of this pest with particular thanks to authors of articles and aforementioned websites used as references, including “Perspective: shedding light on spotted lanternfly impacts in the USA” by Julie M. Urban, “Dispersal of Lycorma delicatula (Hemiptera: Fulgoridae) Nymphs Through Contiguous, Deciduous Forest” by Joseph A. Keller, Anne E. Johnson, Osariyekemwen Uyi, Sarah Wurzbacher, David Long, and Kelli Hoover, “The Establishment Risk of Lycorma delicatula (Hemiptera: Fulgoridae) in the United States and Globally” by Tewodros T. Wakie, Lisa G. Neven, Wee L. Yee, and Zhaozhi Lu, and “Applications of Beauveria bassiana (Hypocreales: Cordycipitaceae) to Control Populations of Spotted Lanternfly (Hemiptera: Fulgoridae), in Semi-Natural Landscapes and on Grapevines” by Eric H. Clifton, Ann E. Hajek, Nina E. Jenkins, Richard T. Roush, John P. Rost, and David J. Biddinger. Thanks to Brian Eshenaur and the entire team at the New York State Integrated Pest Management Program of Cornell University for providing the updated maps of spotted lanternfly in the US.

From the mailbag - large scary bees buzzing the backyard? Nah, Green June Beetles, Cotinus nitida

 

Caught by the lens of a cell phone as it rested on some bare soil, this image reveals a Green June Beetle that was buzzing above the lawn. Credit: Chris Millward

 

This week we leave the world of worms and return to the realm of six-legged creatures. Back in mid-July, an inquisitive mathematics teacher shared an image of a striking large green scarab beetle groveling in a bare patch of soil. On recon to the property, I was amazed to see scores of large bumble bee–like fliers zooming just above the surface of the turf. Occasionally one of the fliers would dive-bomb into the grass. After examining one such crash site, I realized these were not demented bumble bees, rather they were very large scarab beetles known as Green June Beetles. The flight patterns and buzzing sounds of Green June Beetle adults are strongly reminiscent of large bumble bees. Perhaps, these behaviors are a clever way to ward off would-be predators that learned not to mess with large buzzing, stinging insects. 

At first glance, this backyard appears perilously infested with large swarming insects that just might sting. On closer inspection, these aerial acrobats turned out to be harmless Green June Beetles. They love to eat fresh fruit. This one took a break from its antics to enjoy a sweet cherry I placed in the lawn.

While most beetles spread their hard outer wings to fly, Green June beetle and their kin simply lift their hardened outer wings, expand membranous hind wings, and take off. Male beetles zoom in the morning as they search for mates. Females also fly low as they search for suitable places to deposit eggs in the soil. Once the female locates a favorable spot, she burrows several inches into the earth, makes a large sticky ball of soil and proteinaceous goop (technical term), and deposits eggs in it. Eggs hatch in a few days into small C-shaped white grubs. During the day the white grubs rest in a burrow underground, but at night they move to the surface of the earth to eat decaying organic matter. 

Watch as green June beetles take flight first at full speed and then slowed by 95%. See the unusual position of the wings where hard outer wings remain closed and membranous hind wings extend outward and are used for flight.

These unusually large grubs have an equally unusual mode of getting from place to place. Although Green June Beetle grubs have well developed legs on their thorax, legs are not the primary mode of locomotion when they rise from the earth. These wiggly critters have a series of stout hairs on the upper surface of their back. To move above ground, the grub rolls on its back and with peristaltic motions it wriggles across the surface of the ground. The stout dorsal hairs contact the substrate and provide ample traction for surprisingly rapid movement. 

Using a backstroke even Michael Phelps would admire, a Green June Beetle larva races across my patio.

Doesn’t this Green June Beetle look lovely posed on a flowerhead?

Soils with organic mulches and farm fields that receive applications of manure are highly attractive to the egg-laying females and may be loaded with grubs. The lawn which inspired this episode receives liberal nutrient subsidies from the household pooch and trespassing deer. Unlike their more destructive relatives, Japanese beetles, Asiatic Garden Beetles, and Oriental Beetles, Green June Beetles are not serious pests of roses, lindens, or other plants. The burrowing activity of grubs causes problems on highly managed turf in golf courses. Their primary foods are thin-skinned fruits such as berries and grapes. I have also observed several adults congregating on a wounded tree to slurp fermenting exudates. Fresh fruit and fermenting beverages sound just fine on a hot summer’s day. These Green June Beetles just may be a bit smarter than we think. 

Acknowledgements 

We thank Chris Millward for sharing the image of the Green June Beetle that inspired this episode. Information for this Bug of the Week came from Daniel Potter’s excellent reference book “Destructive Turfgrass Pests”, and the interesting article “Mimicry of Hymenoptera by Beetles with Unconventional Flight” by R.E. Silberglied and T. Eisner.