European hornet, Hornet
No status defined
Value of species
The largest eusocial wasp in Europe and the largest vespine in North America. It is actually the only true hornet found in North America. V. crabro is usually regarded as a pest by those humans who come into contact with it. Vespines, like V. crabro, are known for making nests out of surrounding plant materials and other fibers to create intricate paper nests. Unlike most other vespines, reproductive suppression involves worker policing instead of queen pheromone control as was previously thought.
This species stings in response to being stepped on or grabbed, but generally avoids conflict. It is also defensive of its hive and can be aggressive around food sources. European hornets are carnivorous and hunt large insects such as beetles, wasps, large moths, dragonflies and mantises. However, mutual predation between medium-sized hornets and robberfly (Asilidae) is often reported. Care should be taken when they are encountered in these circumstances, as they may sting without warning. The pain from the sting may persist for several days with attendant swelling. Victims may wish to seek medical attention in case of an allergic reaction.
As the name, European hornet, implies, V. crabro used to be found only in Eurasia. Nests ranged from Japan to the United Kingdom. However, Saussure reported that V. crabro was introduced to North America in the mid-19th century, and it is now well-established. More recently in 2010, they were found to have also made their way into Guatemala. The few nests found in Guatemala were thought to be introduced accidentally, rather recently, since these were the first documented occurrences.
V. crabro prefers to build nests in dark places, usually hollow tree trunks. After the site has been chosen, the queen lays eggs in the combs inside the nest. The workers dispose of any eggs that are not from their queen directly, due to worker policing. Based on laboratory data, the egg-laying rate is roughly 2.31 eggs per day. However, in this same lab nest, the cell construction rate was only 1.63 cells per day.
As the year progresses, the colony changes its style of obtaining food for both the larvae and adults. In April, when the queen normally lays her eggs, the workers actively go out and forage. However, typically around the fall season, a change is observed in the colony as the foraging workers turn into scavengers. Instead of putting forth the effort to find food sources, the workers try to take what is more easily available. For example, European hornets have been seen hovering around garbage cans and picnic areas in the fall.