See Asian Giant Hornet Fact Guide by James Mason in Virginia Tech’s Department of Entomology for a summary of risk, and an excellent pairing of photos of this species with species likely to be confused.
Fig. 1a, b. Asian giant hornet, Vespa mandarinia, courtesy of USDA-APHIS
Recently a nest of the Asian giant hornet was found in Washington State, using a new approach to nest detection. Workers are captured and fitted with tracking devices, leading investigators to the nest. I've had some questions about this hornet, and so I'm reposting an article from May 2020. Follow below!
I’d like to say a few words about another invasive insect that has been in the news lately, and is generating questions (I promised myself I would not say generating a lot of buzz, and I’m going to hold to that!). This is the Asian giant hornet, Vespa mandarinia. A recent newspaper article (Baker 2020) used a nickname for this insect – murder hornet - that is a literal translation of a Japanese nickname. One needs to be careful about common names and nicknames of insects. Velvet ants are neither velvet nor ants, but a family of wasps that have been referred to as “cow-killers”, even though they are no threat to cattle. The Asian giant hornet was referred to as a murder hornet to elicit interest in readers, but people have really latched onto it, going beyond mere “elicited interest”! This is the world’s largest hornet, about 45 mm long, about 1.8 inches (queens are larger, about 50 mm, or 2 inches. Their main food consists mainly of insects, e.g. other wasps, beetles and mantises.
Several points need to be made about this wasp:
1) It is nowhere close to Virginia or anywhere else in our region. The discovery was made last December in northwestern Washington State, after being found earlier in the fall in adjacent British Columbia.
2) The known infestation in the US currently consists of two dead wasps found. There was likely a nest that gave rise to these individuals, but it has not been common even where discovered.
3) The US discoveries were across the water from a hive that was discovered in Nanaimo, on Vancouver Island in British Columbia in September. That hive was found and destroyed (Bérubé 2020). A genetic analysis has shown that the wasps from the BC and WA sites were not from the same hive.
4) In Japan about 40-50 people die from stings from this species. In the US from 2014-2017, annual deaths from bee and wasp stings ranged from 43-89 (CDC 2019).
5) The main threat is to honey bees. The wasp workers will attack honey bee hives in order to steal brood. Beekeepers and entomologists in Washington State will be working to find and destroy nests while it is still in a restricted geographical range.
The threat to honey bees: This wasp feeds on a wide range of insects, but in late summer and into the fall will attack honey bee hives. There are several phases of wasp attack against the hive (Matsuura and Sakagami 1973). Early in the cycle, there is a hunting phase, where wasps will wait near hives and attack individual bees as they leave the nest. Later this will progress to a slaughter phase, where groups of wasps will attack worker bees, biting and killing the bees until there is no more defense. This leads to the occupation phase, where bees enter and remove bee pupae to serve as food for the wasp brood. Honey is not taken. During this occupation phase, the wasps become more aggressively defensive and will attack perceived intruders. European honey bees (Apis mellifera) are much more vulnerable than Japanese honey bees (Apis cerana).
You may have read about a response of Japanese honey bees when their hive is threatened by the wasp. I’ll expand on this by including links I have been using in my course on Insect Structure and Function, showing how the insects’ circulatory system is coopted for another use. First – the threat posed to our main honey bee, the European A. mellifera. This bee did not evolve with Asian giant hornet, and so has no effective defense. A scout wasp finds and marks a bee hive, and her nestmates soon arrive to attack the hive. After eliminating the workers, the brood is taken to feed the wasp brood back in their nest. Here is the video depicting the threat to European bees:
The Asian honey bee, A. cerana, has evolved with the hornet, and has evolved a defense – think of this as an evolutionary arms race. When the scout wasp finds the nest, the bees swarm over the invader, vibrate their wing muscles, and generate a heat that heat the blood. This heat is dissipated through the cuticle, or exoskeleton, of the bees. While the temperature generated is tolerable to the bees, it is lethal to the wasp, killing the intruder before her nestmates learn of the hive. Here is the link to a video on that response by A. cerana:
How can Asian giant hornet be managed?: In Japan, several types of approaches to managing Asian giant hornet in bee yards were discussed and summarized by Matsuura and Sakagami (1973) as falling into six categories: 1) Beating to death, 2) Removal of hornet nests, 3) Bait trapping, 4) Mass poisoning, 5) trapping at hive entrances, 6) Protective screens. Many of these were developed on an ad hoc basis by beekeepers and need to be further tested.
Telling Asian giant hornet from wasps that are already here: Because of the widespread public concern over Asian giant hornet, it will be very useful to be able to differentiate that species from insects that may be confused. In addition to size, note the shape of the yellow to yellow-orange head, the yellow stripes on the abdomen (Figs. 1a,b), the dark antennae with yellow-orange scape (first or basal segment), and a wide gena (the area behind the eye). Here is a link to a graphic that compares the Asian giant hornet to several other wasps:
This graphic was developed in Washington State, where the Asian giant hornet was found. Some of the species shown are western species, but we have similar ones here in the east. For example, the yellowjacket shown is Vespula pensylvanica, which, despite its scientific name, is mainly a western species. However, it is similar in size to our eastern species, Vespula vulgaris among others.
Another big wasp, likely to be confused: Because of its large size, the wasp that will most likely be mistaken to be the Asian giant hornet is the European hornet, Vespa crabro. That species was introduced into the US in the middle 1800s, and is now present in much of the east (Akre et al. 1981). It usually not very aggressive, and does not cause the problems that yellowjackets do. This wasp is commonly seen. Note the projections of dark area that cut into the leading edge of yellow striping, a dark area that is somewhat doorknob shaped. This can be seen in the photo (Fig. 2) at the beginning of the post and in the illustration below (Fig. 3).
Fig. 3. Top of gaster (abdomen) of the European hornet, taken from Akre et al. (1981)
See our new fact guide for Asian giant hornet: To help address the public concern, the Entomology Department at Virginia Tech has published a fact guide to the Asian giant hornet (Mason 2020) (https://www.ento.vt.edu/News/Asian_Giant_Hornet.html). In this article, photos of the Asian giant hornet are paired with photos of several wasps that may cause confusion. Note the differences in size and color pattern. I’ve seen one news article that used the European hornet photo mis-labeled as the Asian giant hornet, creating the potential for further confusion.
In summary, two dead adults of Asian giant hornets were found in Washington State in December, shortly after a nest was found and destroyed in nearby British Columbia. The locality of the originating nest of the US finds is not known, but there is so far no definitive proof that Asian giant hornet is established in this country. The main threat from this wasp is to honey bee hives. Beekeepers are working with the Washington Department of Agriculture and Washington State University to find, and if necessary, work to eradicate this species. It is not expected in the eastern states in the foreseeable future. More important risk to honey bees continues to be parasitic mites and the viruses they transmit, loss of foraging diversity, lack of genetic diversity, pesticides, and overwork!
References for added enjoyment!
Akre, R. D., A. Greene, J. F. MacDonald, P. J. Landolt, and H. G. Davis. 1981. The Yellowjackets of America North of Mexico. U. S. Dept. Agric. Handbook 552: 102 p.
Baker, M. 2020. 'Murder hornets' in the U.S.: The rush to stop the Asian giant hornet. The New York TImes.
Bérubé, C. 2020. Giant alien insect invasion averted - Canadian beekeepers thwart apicultural disaster. Am. Bee J. 160: 209-214.
CDC. 2019. QuickStats: Number of deaths from hornet, wasp, and bee stings, among males and females — National Vital Statistics System, United States, 2000–2017. MMWR Morb. Mortal. Wkly. Rep. 68 649.
Mason, J. 2020. Asian giant hornet fact guide, Department of Entomology News.
Matsuura, M., and S. F. Sakagami. 1973. A bionomic sketch of the giant hornet, Vespa mandarinia, a serious pest for Japanese apiculture. J. Fac. Sci. Hokkaido Univ. Ser 6, Zool. 19: 125-162.
Friday, July 9, 2021
We are at crucial stage of development for our population of spotted lanternfly, both in terms of range expansion and seasonal phenology. You may remember that at the end of last season, we had detected SLF at a commercial vineyard for the first time, in a vineyard north of Winchester (we had earlier detected it on a table grape planting in Winchester). This week we found fourth instar nymphs at two commercial vineyards southwest of Winchester. Dr. Johanna Elsensohn, a post doctoral researcher with USDA-ARS, found a single nymph on a vine. At both of these Frederick County vineyards we found nymphs on tree of heaven on both sides of the blocks – the vineyards are essentially surrounded!
Yesterday, the first adults of SLF for this season were reported. This is an important time of the season, since the adult stage is the main dispersal stage. From now until fall, there will be a time of movement into vineyard blocks if SLF is established in the area. Growers in such areas should be watchful. Adults will form large feeding aggregations, and can impost a large drain on the vine.
Fig. 3-4. Spotted lanternfly fourth instar nymphs on tree of heaven surrounding a vineyard.
In both of these vineyards, there were stands of young tree of heaven that had grown from cut trees. It will be helpful to remove tree of heaven, but it is important to not simply cut the trees with out supplemental herbicide treatment, because of the way these trees regenerate. Figs. 2 and 3 show nymphs on such small trees (Figs. 1 and 4 contain nymphs on mature trees). We are fortunate in having only a single generation of SLF. If we start the season with a low population of young nymphs, it is unlikely that significant immigration will occur, and additional sprays may not be needed. This can change with the mobility of winged adults.
This year is likely to be a year of additional commercial vineyards with populations of SLF. Apple and peach orchards may also see feeding aggregations, but these may be transient. Hops are also fed upon, but more information is needed on duration and severity, Please let me know of observations at your plantings.
Wednesday, June 30, 2021
This year's emergence: This emergence of Brood X periodical cicada has now pretty much run its course – the adult stage anyway. If you have young fruit trees, it might be helpful to prune off damaged branches – this would prevent the nymphs from establishing on roots, helpful in the first formative years of the tree. Eggs normally hatch 6-10 weeks after oviposition. For us in Virginia, this was mainly a northern Virginia issue. Brood X extends up through eastern Pennsylvania and New Jersey (remember this when you get to the hot topic note toward the end!) There were also populations of Brood X south of Virginia (parts of North Carolina, Tennessee and Georgia). Here are the maps for Broods IX and X:
The broods were characterized and named by the USDA entomologist Charles Marlatt in 1907 (Marlatt 1907). But while Marlatt made a great formal study of these insects and determined the geographical broods, he was not the first to determine the 17-year cycle. A free African-American naturalist, Benjamin Banneker, living in Maryland, born in 1731, reported this after an 1800 emergence (Barber and Nkwanta 2014). He successfully predicted subsequent emergences. Both of these individuals played other important roles – Banneker helped survey the borders of Washington DC, and Marlatt led the creation of the first regulations designed to protect us from invasive pests).
There are three Magicicada species that make up each brood of periodical cicada. The local species composition can very a lot, even within a county. Last week we sampled cicadas in Frederick County: at Fort Collier in Winchester, 94% were composed of M. cassini (34:2), while at Star Tannery in the southwestern part of the county, 76% were M. septendecim (16:5). M. cassini are smaller, with the underside of the abdomen completely black, compared with the larger M. septendecim, with red on each sclerite.
While M. cassini may lay their eggs in smaller branches, I’ve seen no comparison of the economic impact of the species, and they are treated equivalently.
It was originally thought that most egg-laying occurred distal to the clusters of grapevines, and so on grape, injury was most important on young vines. Clearly some of the injury we saw was basal to clusters, and those clusters will be lost. While young vines are at particular risk, there is clear economic impact to bearing vines. At this point, it is not recommended to prune out affected shoots, but rather wait until winter pruning.
Coming attractions: The adults of this emergence of Brood X are now a recent memory. As I’ve pointed out in extension presentations, it is wise to avoid planting a new orchard or vineyard a year or two before an anticipated emergence. However, we don’t usually give this warning long enough in advance for sufficient planning, given the lead time needed by nurseries, to get desired scion/rootstock combinations. Here is a listing in order of appearance of broods relevant to Virginia. The most important ones will likely be XIX, II, IX and X. Click on the Brood numbers to see a map.
Brood XIX (13 year): (Southside Virginia) The Great Southern Brood (2024)
Brood XIV: southern OH, KE, TN, MA, MD, NC, PA, northern GA, southwestern VA and WV, parts of NY and NJ (2025)
Brood I: The Blue Ridge Brood: Western VA, WV (2029)
Brood II: East Coast Brood: CT, MD, NC, NJ, NY, PA, DA, VA, DC. (2030)
Brood V: eastern OH, western MD, southwestern PA, northwestern VA, WV, NY (Suffolk Co.) (2033)
Brood IX: southwestern VA, southern WV, western NC (2037)
Brood X: The Great Eastern Brood: NY, NJ, PA, DE, MD, DC, VA, WV, NC, GA, TN, KE, OH, IN, IL, MI (2038)
Addressing a hot topic: Another issue has been broached in the news in the past few days that I would like to comment on. There has been a recent wave of unexplained bird deaths and illness in northern Virginia. Symptoms include blindness or crusty eyes, and neurological problems. The idea was postulated that eating cicadas was responsible for this bird morbidity/mortality. This is circumstantial at best. There were no such problems noted last year in Brood IX in southwest Virginia, nor in earlier emergences of Brood X in northern Virginia.
Cicadas have long been considered a nontoxic food for birds (Leonard 1964, Steward et al. 1988, Williams and Simon 1995). Birds feeding on cicadas have included European starling, common grackles, American robin, wood thrush, blue jay, yellow-billed and black-billed cuckoos, red-winged blackbirds, house sparrow, redheaded woodpecker, tufted titmouse, vireos, terns, laughing gull and ducks. I birded last year with friends in areas of Brood IX adult periodical cicada activity, and we saw no unusual bird behavior (the worst thing was not being able to hear birds above the cicada singing!). Periodical cicadas present an important part of nutrient cycling in forests, and are a nutritional resources for predators (Wheeler et al. 1992).
There is an entomopathogenic fungus, Massospora, that may provide some natural mortality to periodical cicadas. There are compounds in Massospora that are psychoactive in cicadas, causing them to change their behavior (Boyce et al. 2019). One compound in Massospora, cathinone (Boyce et al. 2019), has been known to have psychoactive properties in humans (Langman and Jannetto 2020). But there is no record of eating Massospora-infected cicadas being harmful to birds. Moreover, Massospora is a natural component of the system, and unusual bird maladies are not reported following cicada emergences.
One interview (linked above) speculated whether birds might be picking up insecticides or heavy metals from sprayed cicadas. In an earlier study (Clark 1992), cicadas were not found to be a source of significant levels of organochlorine insecticides or heavy metals for birds. Organochlorines have been replaced by other classes of chemistry, but that group was longer lived, and would bioaccumulate. Modern insecticides should pose less of a hazard in this regard.
So in summary, here are my thoughts on cicada involvement with the bird death/sickness syndrome. If the situation changes, or new information becomes available I’ll let you know:
• There was no issue with bird mortality/morbidity with last year's brood IX, nor northern Virginia Brood X last time.
• Massospora has been a part of the landscape for a long time, with no apparent link to birds.
• There was no apparent bird problem in PA or NJ, nor Tennessee or North Carolina, where Brood X was abundant. Note: Some increasing bird mortality was seen in southern NJ after cicadas had disappeared, well after the outbreak in northern Virginia. This weakens the case for synchrony between cicadas and bird deaths.
• There have been changes in pesticides used over the years, but from last year in Brood IX, there wouldn't be any difference with this year in Brood X.
• If cicadas, fungus, or pesticides are involved, there must be some other environmental change to shift their importance.
Reporting Bird Mortality: The Department of Wildlife Resources has created a reporting form for cases of sick or dead birds:
Barber, J. E., and A. Nkwanta. 2014. Benjamin Banneker's original handwritten document: Observations and study of the cicada. Journal of Humanistic Mathematics 4: 112-122.
Boyce, G. R., E. Gluck-Thaler, J. C. Slot, J. E. Stajich, W. J. Davis, T. Y. James, J. R. Cooley, D. G. Panaccione, J. Eilenberg, H. H. De Fine Licht, A. M. Macias, M. C. Berger, K. L. Wickert, C. M. Stauder, E. J. Spahr, M. D. Maust, A. M. Metheny, C. Simon, G. Kritsky, K. T. Hodge, R. A. Humberi, GullionT., D. P. G. Short, T. Kijimoto, D. Mozgai, N. Arguedas, and M. T. Kassona. 2019. Psychoactive plant- and mushroom-associated alkaloids from two behavior modifying cicada pathogens. Fungal Ecol. 41: 147-164.
Clark, D. R. 1992. Organochlorines and heavy metals in 17-year cicadas pose no apparent dietary threat to birds. Environ. Monit. Assess. 20: 47–54.
Langman, L. J., and P. J. Jannetto. 2020. Toxicology and the clinical laboratory pp. 917-951. In W. Clarke and M. A. Marzinke (eds.), Contemporary Practice in Clinical Chemistry. 4th Ed. Elsevier.
Leonard, D. E. 1964. Biology and ecology of Magicicada septendecim (L.) (hemiptera: Cicadidae). J. New York Entomol. Soc. 72: 19-23.
Marlatt, C. L. 1907. The periodical cicada. U. S. Dept. Agric. Bur. Entomol. Bull. 71: 1-181. Steward, V. B., K. G. Smith, and F. M. Stephen. 1988. Red-winged blackbird predation on periodical cicadas (Cicadidae Magicicada spp.) - Bird behavior and cicada responses. Oecologia 76: 348-352.
Wheeler, G. L., K. S. Williams, and K. G. Smith. 1992. Role of periodical cicadas (Homoptera: Cicadidae: Magicicada) in forest nutrient cycles. Forest Ecol. Manag. 51: 339-346.
Williams, K. S., and C. Simon. 1995. The ecology, behavior, and evolution of periodical cicadas. Annu. Rev. Entomol. 40: 269-295.
Thursday, June 10, 2021
Hello, everyone, Just a note on something many of you are aware of - periodical cicadas are now actively laying eggs in grapevines in northern Virginia vineyards. Mature vines have been attractive as well as young vines. Adults are normally active for about 6 weeks. The first report of adults emerging from soil was on April 28, but this was quickly followed by a period of cool temperatures, greatly slowing cicada development. Just a few words on effective materials. Pyrethroids like Danitol and Baythroid are among the most effective materials. Assail, Sevin and Surround also have activity - some materials that are somewhat less effective have the benefit of less risk of inducing secondary pest outbreaks - especially mealybugs and mites. If you opt to use pyrethroids pay close attention to secondary pests for the subsequent weeks. More later, Doug
Thursday, May 20, 2021
Thursday, February 18, 2021
Hello, everyone, Because of the inclement weather today, the state berry school I posted a few days ago, has been rescheduled. The new dates for the Virginia Berry School are Thursday, March 4th through Friday, March 5th. If you are registered already, you do not need to change anything, the link sent by VSU is still valid to log in. If you cannot attend on those days, the sessions will be available online after the event is over for viewing. If you know of anyone who still wants to register, we have reopened registration (https://www.ext.vsu.edu/events/2021/02/18/berry-school). If you need a refund because you no longer wish to attend, please contact Jessica Harris (firstname.lastname@example.org) and you will receive a full refund. We hope to see you there! Doug P.
See Asian Giant Hornet Fact Guide by James Mason in Virginia Tech’s Department of Entomology for a summary of risk, and an excellent pairi...
Virginia Cooperative Extension programs and employment are open to all, regardless of age, color, disability, gender, gender identity, gender expression, national origin, political affiliation, race, religion, sexual orientation, genetic information, veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.