Mesostigmata

 ( Arachnid Orders ) 

The soil-dwelling Mesostigmata are not as abundant as Oribatida or Prostigmata that also occur in this habitat, but they are still ubiquitous in soil and may be important predators. Larger species tend to be predators of small arthropods or arthropod eggs, whereas smaller species prey on . Size of these mesostigmatans decreases with soil depth: plant litter and humus have large species such as Veigaia (Veigaiidae), the humus-soil interface has smaller species like Dendrolaelaps (Digamasellidae) and the mineral soil has the tiny Rhodacarellus (Rhodacaridae).

A few species are known from freshwater habitats, such as wet soil, , waterside vegetation and sewage filter-beds. These appear to move by crawling as no species are known to swim. Some species are known to prey on mosquito eggs and one species was reared on a diet of nematodes.

The parasitic Mesostigmata are mostly in superfamily Dermanyssoidea. These include parasites of invertebrates (e.g. Varroidae) and of vertebrates (other families), as well as both ectoparasites (external) and endoparasites (internal).

Phoresis, the temporary attachment of a smaller animal to a larger one for travel, is common in the Mesostigmata. For example, the freshwater species are phoretic on flies of families Crane fly, Ceratopogonidae, and Culicidae.

Similarly, the red mite ( Dermanyssus gallinae) feeds on the blood of birds, including poultry (, Domestic turkey, ) and wild birds. It reduces animal health, welfare and production.

In agriculture, soil-dwelling mesostigmatans are important predators of nematodes, and insect larvae, while plant-dwelling mesostigmatans control pests such as .