Hornets are the largest of the wasp family with about 20 species across the world. Most species are in the jungles of Asia but are also common in Europe, Africa as well as North America where Hornets were introduced accidentally by European settlers around 1840.
Like Bees and wasps they are a social insect creating a hive or Grist from chewed wood. They have a ferocious reputation and like many social insects males are rare. A Queen will dominate the hive served by female drones who cannot reproduce, these warrior females build the hive, hunt and gather food (Hornets are omnivores) the few males die quickly after mating with the queen.
Adult hornets cannot absorb solid proteins but will hunt other insects to feed the young larvae, killing other insects, often ones larger than themselves and then cut up the prey into a protein mush which is then fed to the young larvae.
They mainly hunt flies but have even been known to attack other insect predators such as prey mantis and dragonflies; once the prey is killed they cut off nutrient poor sections such as wings and legs to leave the body. They will also feed on tree sap and during hot spells bring water back to the hive to cool it. Bizarrely the larvae also give back to the adult feeder a chemical stimulant mix within their salvia (vespid ammo acid mixture (Vaam), this increased the hornet drones stamina and energy with a drone being able to fly at speeds of 25mph and cover an distance of 60 miles a day.
In colder climates the Hornet nests only last one season with a new generation of Queens and eggs seeking settler from the cold inside trees or inside human buildings, emerging in spring to quickly build a new hive and start the cycle again with the Queen producing a new set of queens, males and workers before dying.
The aggressive reputation of hornets is not undeserved as they will fight to protect the hive and young and due to their size (up to 1.8 inches or 4.5 cm long) have a potent sting but their danger to humans has been exaggerated, in fact the European Hornets sting is less toxic than a bee, although some Hornet species are among the most venomous insects (such as the Japanese giant Hornet). All Hornets can bite and sting at the same time and do not die after stinging as their sting is used to hunt prey not to defend against mammals like a bee’s sting. In some European countries such as German they are a protected species due to their role in the eco system.
When encountering a nest Hornets may attack if;
A human approaches with a meter or so of the nest
Loud noises or touching the nest
Killing a hornet near the nest (as chemical alarm signal is released on death)
Breathing on the nest (as they are very sensitive to smell and pheromones)
Rapid air movements (as they are also sensitive to air pressure changes as part of the hunting ability)
European site dedicated to the study and protection of Hornets