The Asian hornet, smaller than our native species, European hornet, measures around 25mm in length (workers), while queens reach 30mm. Its predominantly black abdomen is distinguished by a yellow band on the fourth segment. Also recognizable by its yellow legs, it’s commonly referred to as the yellow-legged hornet, and its face exhibits an orange hue complemented by two brownish-red compound eyes.
After hibernation in spring the queen will emerge and seek out an appropriate sugary food source in order to build up energy to commence building a small embryonic nest. During construction of the nest, she is alone and vulnerable, but she will rapidly begin laying eggs to produce the future workforce. As the colony and nest size increases, a larger nest is either established around the embryonic nest or they relocate and build elsewhere.
An average colony produces 6,000 individuals in a single season. While adult hornets primarily sustain themselves on carbohydrate sources from nectar, larval secretions, or ripe fruits, they must continuously forage for protein to feed the developing brood. This protein is obtained in the form of a ‘flesh pellet,’ a small piece of proteinaceous material carved out from the protein-rich thorax of a captured arthropod or from carrion. From July onwards, predation by Asian hornets on honey bee colonies begins and escalates until late November, with hornets observed hovering outside hive entrances, awaiting returning foragers, a behaviour known as “hawking.” Upon catching a returning bee they make the flesh pellet by removing the wings, legs, head and abdomen. They transport the flesh pellet back to their nest where it is chewed into a sticky liquid and fed to their own larvae.
During autumn, the nest’s priorities shift from foraging and nest expansion to producing on average 350 potential gynes (queens) and male hornets for mating, however, of these potential queens, only a small amount will successfully mate and make it through winter. After the mating period, the newly fertilised queens will leave the nest and find somewhere suitable to over-winter, while the old queen will die, leaving the nest to dwindle and die off. The following spring, the founding queen will begin building her new colony and the process begins again.