The European hornet Vespa crabro, commonly known simply as the "hornet", is the largest European eusocial wasp. The queen measures 25 to 35 mm (1–1.4 in) long; males and workers are smaller
The Asian giant hornet, Vespa mandarinia, also known as the Japanese hornet and known colloquially as the yak-killer hornet, is the world's largest hornet, native to temperate and tropical Eastern Asia. Its body length is approximately 50 mm (2 in), with a wingspan of about 76 mm (3 in).Queens may reach a length of 55 mm (2.2 in).
The scariest thing I found out about the asian hornet was this:
The hornets can devastate a colony of honey bees: a single hornet can kill as many as 40 honey bees per minute thanks to their large mandibles which can quickly strike and decapitate a bee. It takes only a few of these hornets a few hours to exterminate the population of a 30,000-member hive, leaving a trail of severed insect heads and limbs.
The stinger of the Asian giant hornet is about 6 mm (¼ in) in length,and injects an especially potent venom that contains, like many bee and wasp venoms, a cytolytic peptide (specifically, a mastoparan) that can damage tissue by stimulating phospholipase action, in addition to its own intrinsic phospholipase.Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling "like a hot nail being driven into my leg."
An allergic human stung by the giant hornet may die from an allergic reaction to the venom, but the venom contains a neurotoxin called mandaratoxin which can be lethal even to people who are not allergic if the dose is sufficient. Between 20 and 40 people die each year in Japan after being stung by giant hornets.