Note: The annual life cycle of Vespa velutina can vary depending on geographic location and local environmental conditions. The following information was from research conducted in Europe. The timing here in Southern Georgia may or may not follow this pattern.
Species Name: Vespa velutina
Common Name: Asian Hornet (Europe), Yellow Legged Hornet (United States)
Vespa velutina, commonly known as the Asian hornet or yellow legged hornet, is an invasive species of hornet native to Southeast Asia. It has become a significant ecological concern in some regions due to its impact on native pollinators and potential harm to human populations.
Annual Life Cycle:
- Winter Phase (Late Autumn to Early Spring):
- During the winter, only fertilized queens survive.
- Queens find shelter in protected areas, such as tree hollows or buildings, to avoid the cold.
- They enter a state of diapause, a form of dormancy, to conserve energy.
The Yellow legged hornet’s ability to hibernate practically anywhere that’s small and dark poses an intriguing twist to their tale. This characteristic enables them to be transported across long distances while in hibernation. A notable example is how the yellow legged hornet likely made its way to south-west France: hitching a ride in Bonsai pots from China. This journey likely repeated itself, introducing the species to Belgium, Portugal, and Italy – all of which are quite a distance from the original source nests in France.
- Spring Phase (Late Winter to Early Spring):
- As temperatures rise and food becomes available, the queens emerge from diapause.
- Queens search for suitable nesting sites to establish new colonies.
- Nests are usually constructed in high places like trees or buildings.
As the following spring dawns, the foundresses awaken and disperse across various distances to establish new primary nests. Although the specifics of this behavior remain shrouded in mystery, it’s believed to be a crucial component of the invading the yellow legged hornet’s expansion across the landscape.
- Early Summer Phase (Spring to Early Summer):
- Once a suitable nest site is found, the queen constructs a small paper nest and lays her first eggs.
- The queen incubates the eggs and later cares for the emerging larvae.
- As workers hatch, they take over the tasks of foraging for food and expanding the nest.
Primary nests mark the beginnings of a colony, built by the founding queen to lay her initial eggs. These nests are somewhat transient, serving their purpose until the first workers emerge. Approximately 77% of primary nests were found in man-made structures.
- Mid-Summer Phase (Summer):
- The colony rapidly grows in size as more workers emerge and the nest expands.
- The primary focus is on gathering food, which includes insects, nectar, and fruits.
- Worker hornets also defend the nest and the surrounding area from potential threats.
As the colony burgeons, a more expansive domicile becomes necessary. The growing colony ultimately abandons the primary nest to construct a significantly larger, permanent secondary nest. This transition occurs by the end of July. Approximately 74% of these secondary nests were found in trees. Oaks and Pines were the most common trees along with plane trees, alder, cedar, and tulip trees. 5% were found in other natural structures with about 22% found in man-made structures.
The colony flourishes throughout the early and mid-summer, driven by the relentless efforts of the growing workforce. The primary focus shifts to gathering food, which includes insects, nectar, and fruits. The workers also stand guard, defending their nest and surroundings
- Late Summer Phase (Late Summer to Early Autumn):
- Reproductive phase begins.
- New queens and males are produced. These reproductive individuals are larger than workers.
- Mating flights occur, where new queens and males mate in mid-air.
- Males die shortly after mating, and new queens start searching for winter shelter.
As autumn approaches, the colony takes a new direction. Reproductive individuals, larger than the workers, come into existence. New queens and males are produced, and the stage is set for a crucial event – mating flights. In these mid-air trysts, new queens and males pair up. Tragically, the males’ lives come to an end soon after, leaving the new queens to bear the torch of the colony’s future.
- Autumn Phase (Autumn):
- The original queen’s focus shifts from egg-laying to producing new reproductive individuals.
- As temperatures drop, worker activity decreases, and the colony’s overall activity declines.
- The colony reaches its peak size just before it starts to decline.
As the season changes, so does the destiny of the colony. The old queen’s role evolves from egg-laying to producing new reproductive individuals. The workforce dwindles, and the once-bustling nest activity takes a calmer turn. The colony reaches its zenith just before the inevitable decline.
Foundresses, on the other hand, embark on a quest to find suitable hibernation spots. Once the transition is complete, the secondary nest lies abandoned and inactive.
- Winter Phase (Late Autumn to Early Spring):
- The old queen and the majority of the workers die due to colder temperatures and reduced food availability.
- The fertilized queens that mated in the previous season seek shelter to survive the winter.
Winter’s chill sets in, and most of the colony succumbs to the cold. But not all is lost. Fertilized queens that mated during the reproductive phase seek refuge for the winter months. These queens represent the the next generation, survivors poised to carry on the the following Spring.
Efforts to manage the yellow legged hornet populations include early detection, destruction of nests, and public awareness campaigns to report sightings. It’s crucial to address the spread of this invasive species to protect local ecosystems and minimize potential harm.
Reporting yellow legged hornet Sightings:
Early detection and reporting of yellow legged hornet sightings are vital for controlling its spread and minimizing its impact. If you suspect you’ve encountered this invasive hornet, here’s what you can do:
- Observe Safely: Keep a safe distance from the hornets and avoid any actions that could provoke them.
- Capture Visual Evidence: If possible, take clear photos or videos of the hornet and its surroundings. This will aid experts in verifying the sighting.
- Note Location and Time: Record the date, time, and specific location of the sighting. This information helps authorities track the spread of the species.
- Report to Authorities: Contact your local agricultural extension office, wildlife agency, or relevant authorities to report the sighting. They will guide you on the appropriate steps to take.
Georgia Department of Agriculture’s (GDA) website has been updated with additional information regarding the yellow-legged hornet and an easily accessible form to report potential sightings. This information is prominently displayed on the GDA homepage. Georgians with additional questions or concerns are encouraged to email firstname.lastname@example.org.
Georgians reporting suspected specimens should include the following information:
- Your name and contact information.
- The location of the sighting/attack.
- The date of the sighting/attack.
- If you can, safely take photograph(s) of the hornet (we generally can only confirm a report with a photo or specimen).
- The location and approximate altitude of the nest if found (Is it in a tree? Approximately how high is the nest?).
- If you have no photo, please include a description of the size of the insect, the color of the head and body, and what it was doing.
- Description of the hive loss/damage (if no photo is available).
- The direction the hornet(s) flew when flying away.
- Franklin, D. N., Brown, M. A., Datta, S., Cuthbertson, A. G. S., Budge, G. E., & Keeling, M. J. (2017). Invasion dynamics of Asian hornet, Vespa velutina (Hymenoptera: Vespidae): a case study of a commune in south-west France. Applied Entomology and Zoology, 52(2), 221-229. DOI: 10.1007/s13355-016-0470-z.
- Rome Q, Muller F, Touret-Alby A, Darrouzet E, Perrard A. (2019). “Population structure and genetic diversity of invasive Vespa velutina (Hymenoptera: Vespidae) in France and South Korea.” Insect Conservation and Diversity, 12(4), 289-297.
- Monceau K, Bonnard O, Thiéry D. (2013). “Vespa velutina: a new invasive predator of honeybees in Europe.” Journal of Pest Science, 86(4), 1-16.