Mesostigmata-
predator soil mites

Mesostigmatans, (order Mesostigmata, superorder Parasitiformes) tend to be well sclerotised, and are fluid feeders, like their cousins, the Prostigmata. Some mesostigmatan families dedicate themselves to parasitic and phoretic encounters with birds, mammals, reptiles and some social insects, such as the infamous varroa mite that parasitises the honey bee. But most are free-living soil predators, merciless and efficient hunters of anything and everything with a cuticle. They are usually fast moving, as befits a top predator, and not particularly coloured, sticking to muted browns and creams. 

As the name might suggest, the stigmata or spiracles of the Mesostigmata are positioned midway on the side of the body, usually associated with a distinctive perotrematal groove.

In some mesostigmatan families, as with some of the prostigmatan Eupodidae, the first pair of legs of the Laelapidae have elongated and developed sensory setae to act as feelers. They use them while hunting, to feel for prey like Collembola and guide them towards their chelicerae. Some species even have a glue-like substance on them to help further entrap their hapless quarry.

Because of their unrelenting and efficient attack capabilities, some families in Mesostigmata are used as biocontrol agents. Phytoeiulsus persimilis is a specific predator of the two-spotted mite, a common pest on house plants and in greenhouses. One adult can eat around seven of its prostigmatan cousins a day.