Myrmecia (ant) encountered before. Based on five species, the median lethal dose (LD) is 0.18–0.35 mg/kg, making it among the most toxic venoms in the insect world. The toxicity of the venom may have evolved due to the intense predation by animals and birds during the day, since "Myrmecia" is primarily diurnal. In Tasmania, 2–3% of the human population is allergic to "M. pilosula" venom. In comparison, only 1.6% people are allergic to the venom of the western honeybee ("Apis mellifera"), and 0.6% to the venom of the European wasp ("Vespula germanica"). In a 2011 Australian ant-venom allergy study, the objective of
Ant to burst from the anterior region of its head, spraying a poisonous, corrosive secretion containing acetophenones and other chemicals that immobilise small insect attackers. The worker subsequently dies. Suicidal defences by workers are also noted in a Brazilian ant, "Forelius pusillus", where a small group of ants leaves the security of the nest after sealing the entrance from the outside each evening. In addition to defence against predators, ants need to protect their colonies from pathogens. Some worker ants maintain the hygiene of the colony and their activities include undertaking or "necrophory", the disposal of dead nest-mates. Oleic acid has