Mites & ticks

Acari

Mites and ticks (the Acari) are the largest group of arachnids, but the smallest in size. Most of the 45,000 described species are less than 1 mm in length.

Paralysis Tick, Ixodes holocyclus, adult female Paralysis tick (Ixodes holocyclus), found along the east coast of Australia.Flat mite, Brevipalpus sp.Flat mite, Brevipalpus sp.

Mites live almost everywhere, are abundant, and do just about anything. In contrast, all ticks are parasites of mammals, birds and reptiles. They’re also much larger than most mites, reaching nearly 30 mm when engorged with blood. Almost 900 species of tick are known, with few new species remaining to be described. In contrast, we think the 44,000 species of mites represents just 5-10% of all described species.

Despite their diversity and abundance most people are unaware of mites, except perhaps dust mites. Ironically, many are blissfully unaware that one or two species of the harmless hair follicle mites infest almost every person.

A lot of mites get bad press for being pests, and such concern is not undeserved. Mites attack plants we use for food and, after harvest, the stored products. They can also transmit disease to these plants as they feed.

Mites also attack animals: mange mites, ear mites, fowl mites and chiggers are all parasitic. Chiggers, also called scrub itch mites, can transmit typhus. Insects and other invertebrates are also parasitised by mites. The most significant of these are the parasites of honey bees, of which Varroa is the most serious.

It’s not all bad, though. Many mites are predatory and some eat the pest mites. Hordes of mites are detritivores, joining in the essential job of turning rotting plants into small particles. Many are beautiful, with intricate patterns and camouflage. They also live in incredible places on animals: the lungs of snakes and birds, the cloaca of turtles, breathing tubes of bees and beetles, eyeballs of bats, ears of moths and inside the quills of birds, to name just a few.

Short-legged Velvet Mites (Trombidioidea) on a moth. Short-legged Velvet Mites (Trombidioidea) on a moth.

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