The Asian giant hornet, Vespa mandarinia, a species native to temperate and tropical Eastern Asia, is the world's largest hornet. Adults can be up to 4.5 cm (1.8 inches) long (queens reach 5.5 cm long) and have a 6mm (0.25 inches) sting which injects a large amount of potent venom. Asian giant hornets can fly up to 100 kilometres in a single day, at speeds of up to 40 kilometres per hour.
The Asian giant hornet is a relentless hunter that preys on other large insects, such as bees, other hornet species, and mantises. Asian giant hornets often attack honey bee (genus Apis) hives with the goal of obtaining the honey bee larvae. A single V. mandarinia scout, sometimes two or three, will cautiously approach the nest, giving off pheromones which will lead the other hornets to the hive's location. Asian giant hornets, which are five times the size and 20 times the weight of a honey bee, can devastate a honey bee colony in a very short time: a single hornet can kill as many as 40 honey bees per minute thanks to its large mandibles. Once a hive is emptied of all defending bees, the hornets feed on the honey and carry the larvae back to feed to their own larvae. The European honeybee (Apis mellifora) has no natural defenses against giant Asian hornets and their hives are especially vulnerable to attack. However, Apis species native to Asia (for example Apis cerana japonica) have evolved strategies for defeating Vespa mandarinia attacks: if they detect a attacker in time the bee colony can form a “bee ball”, surrounding the hornet to very effectively suffocate it. Adult Asian giant hornets cannot digest solid protein, so they do not eat their prey, but chew them into a paste and feed them to their larvae. The adults themselves consume a clear liquid, Vespa amino acid mixture, which is produced by the larvae. The passing of nutrition from larvae to adult wasps is widespread among social vespid wasps, and not restricted to the genus Vespa. The exact amino acid composition varies considerably among species.
In Japan, Asian giant hornets are sometimes eaten raw or fried. Recently, several companies in Asia and Europe have begun to manufacture dietary supplements and energy drinks which contain synthetic versions of Vespa mandarinia larval amino acid secretion. The manufacturers of these products make claims that consuming the larval hornet secretions (marketed as "hornet juice") will enhance human endurance. (Handwerk 2002; Sugahara and Sakamoto 2009; Ono et al. 1995; Wikipedia 2011(a); Wikipedia 2011(b))