A girl has her helmet adjusted on the top of a tank during the Children's Day celebration at a military facility in Bangkok, Thailand January 9, 2016. Army barracks opened their doors to children to interact with their weapons and vehicles as part of the celebration. (Photo by Jorge Silva/Reuters)

A reveller dances during “Lou Queernaval” parade, the first lesbian, gay, bisexual and transgender (LGBT) carnival in France, as part of the Carnival of Nice February 19, 2016. (Photo by Eric Gaillard/Reuters)

Wizz Air's Airbus A-321 flying along the Danibe river during an air show in Budapest, Hungary, May 1, 2016. (Photo by Laszlo Balogh/Reuters)

Hindu devotees, their cheeks pierced with metal rods, wait to participate in a religious procession during Thaipusam festival in Chennai, India, Tuesday, February 3, 2015. Thaipusam, celebrated in honor of Hindu god Lord Murugan, is an annual procession by Hindu devotees seeking blessings, fulfilling vows and offering thanks. (Photo by Arun Sankar K./AP Photo)

A man dressed as Ironman takes a seat in the cafeteria on the second day of the London Super Comic Convention at the ExCel centre in east London, on March 15, 2015. (Photo by Justin Tallis/AFP Photo)

Fireworks light the sky over Copacabana beach during New Year's Eve celebrations in Rio de Janeiro, Brazil, Thursday, January 1, 2016. (Photo by Mauro Pimentel/AP Photo)

A man roasts dog at Langowan traditional market on August 9, 2014 in Langowan, North Sulawesi. The Langowan traditional market is famous for selling a variety of extreme food such as dogs, bats, rats, wild boar, and snakes. (Photo by Putu Sayoga/Getty Images)

Hornets are insects that are the largest eusocial wasps. Some species can reach up to 5.5 cm (2.2 in) in length. The true hornets make up the genus Vespa and are distinguished from other vespines by the width of the vertex (part of the head behind the eyes), which is proportionally larger in Vespa and by the anteriorly rounded gasters (the section of the abdomen behind the wasp waist). The best known species is the European hornet (Vespa crabro), about 2–3.5 cm in length, widely distributed throughout Europe, Russia, North America and Northeast Asia.