There are thousands of species of mites and ticks from the subclass Acari. Mites are small arthropods belonging to the class Arachnida and the subclass Acari. Astigmatina is a cohort of mites in the subclass Acari, mites and ticks. Slugs are parasitised by several organisms, including acari and a wide variety of nematodes. It also has strong antimicrobial qualities, and pheromonal effects in acari and insects. It functions to keep parasites (Acari) out of the tympanal cavity. The Acari (or Acarina ) are a taxon of arachnids that contains mites and ticks. Acaricides are pesticides that kill members of the Acari group, which includes ticks and mites. Up until the 1980s they were thought to be closely related to mites (Acari). The six-legged larva is a feature they share with Acari (see Relationships). Ticks are closely related to the mites, within the subclass Acari. Within the Acari are two superorders&colon; the Acariformes and the Parasitiformes. Along with mites, they constitute the subclass Acari. The Acari are a subclass of the class Arachnida. Historically, mites and ticks were treated as a single order, Acari.