The so-called European hornet, latin Vespa crabro lives in most Europe and North America.
Yellow and black insect, very similar to a wasp, just somewhat larger and more dangerous. They usually nest in protected places, under the roofs, in the attics, sheds, in hollow trees and similar neglected places where they can be undisturbed. The hornet will never attack unprovoked. It will attack an animal or a human only when it feels threatened. In case their colony is in danger, it will try and defend it in a swarm and dosens of stings can happen in those situations. Usually such attacks will be fatal.
The hornet will upon the sting, release a large quantity of its poison, that will cause a burning sensation. In addition, hornet’s sting is longer and wider than the bee’s or wasp’s, which allows it to go deeper under the skin, causing more pain. Most of the deaths is not caused by the toxicity of the poison itself, but rather by a violent alergic reactions of the organism, which can lead to classic symptoms of shock. Those include increased heart-rate, nausea, vomiting, blood-pressure drop, lack of breath etc.
Generally speaking, one hornet’s sting will not be fatal for a man (or a dog), but people with deteriorating health and history of alergies can be in danger. Especially if you’ve been stung around the mouth or in the throat, go see a doctor immediatelly because the swelling in those areas can prove to be fatal. The same goes for the pets, for most healthy pets the sting will just be unpleasant, but older and allergic pets could be in danger.
Antihistamines and corticosteroids will reduce the allergic reaction, giving you more time to get to the doctor.