Wasps often elicit a reaction of fear in people, but these insects are seldom aggressive. Wasps normally defend their nest with a coordinated assault of a perceived threat. Pheromones are used to coordinate the attack, which attract other colony defenders to the intruder. Stings can be painful and also pose a serious health concern to homeowners. Wasps have a distinct ‘U-shape’ to the posterior margin of the pronotum and their forewings fold in half longitudinally. Many species of Vespidae are eusocial, living in a colony comprised of three castes. These castes include queens, female workers and drones. Only the workers are able to sting.