The life stages of the Asian hornet nigrithorax
The Asian hornet's life cycle includes four distinct stages: egg, larva, pupa, and adult.
Francis ITHURBURU , CC BY-SA 3.0 , via Wikimedia Commons
The queen, who survives the winter in hibernation in a protected shelter, wakes up in the spring and chooses a nesting site (often a tree branch or an artificial structure). She builds the primary nest and lays her first eggs there.
The egg: the starting point of the colony
An Asian hornet egg measures approximately one millimeter in diameter, barely the width of a pinhead. The internal temperature of the nest, maintained at around 30°C thanks to the heat generated by the worker hornets, accelerates embryonic development: the egg generally hatches between three and five days after being laid.
The larva: a phase of intensive growth
Once the egg hatches, the tiny larva remains confined to the same cell. At this stage, it is entirely dependent on the food provided by the worker bees. These bees capture flying insects (mainly bees, but also butterflies, beetles, and other small arthropods) and then grind them into a protein-rich paste containing amino acids. They supplement this meal with nectar or honey collected from flowers, thus providing the carbohydrates necessary for energy production.
The larva progresses through several instars (growth stages) over approximately ten to fifteen days. With each molt, it increases in size and develops the internal organs essential for its future metamorphosis. This period of high protein consumption explains why the Asian hornet is considered a formidable predator of honeybees.
The nymph: the silent transformation
When the larva reaches full development, it stops feeding and hermetically seals the cell with papier-mâché. Inside, it enters the pupal stage, during which all the larval tissues are reorganized. The pupa remains immobile and no longer eats; it draws solely on the reserves accumulated during the larval phase.
This process usually lasts between ten and fourteen days, depending on the temperature of the nest (the warmer it is, the faster the metamorphosis). During this period, the adult structures – wings, antennae, mouthparts and reproductive system – gradually form.
The adult: the different roles within the colony
Queen
Francis ITHURBURU , CC BY-SA 3.0 , via Wikimedia Commons
She is the leader of the colony. Unlike the workers, the queen never participates in hunting or building the nest. She lives for several months, but her real strength lies in her ability to survive the winter: when it gets cold, she leaves the nest and settles in a protected shelter (crevice, attic, bread box, etc.) where she hibernates until the following spring to found a new colony.
Female workers
The sterile females that emerge after the queen are called workers. They measure between 25 and 30 mm, possess a functional stinger, but are not capable of reproducing. Their role is multifaceted: they hunt insects to feed the larvae, collect nectar and pollen to nourish the colony, build and maintain the nest, ventilate the cells, and defend the colony against intruders. Their lifespan varies from six to twelve weeks, depending on climatic conditions and workload.
Males (drones)
Males appear in late summer, usually in September. They are smaller (20–25 mm), have a thinner abdomen, and a vestigial stinger used only for occasional defense. Their sole purpose is to leave the nest in search of queens to mate with. After mating, the males die quickly, as they no longer contribute to nest maintenance.
