Prostigmata

Identification to suborder level relies on the presence of prodorsal spiracles (stigmata) and membership in Trombidiformes. Distinguishing Prostigmata from Sarcoptiformes (Oribatida and Astigmata) requires examining stigmata position—Prostigmata have anterior spiracles, while Sarcoptiformes lack these or have different respiratory structures. Within Prostigmata, major groups are recognizable by leg number: Eriophyoidea have four legs (unique among mites), while all other Prostigmata have eight legs as adults. Superfamily-level identification requires specialized knowledge of cheliceral structure, palp morphology, and habitat association.

Occupies remarkably diverse environments. Terrestrial forms inhabit soil (agricultural fields, burned prairies, tidal marshlands, Antarctic soils), leaf litter, mosses, lichens, and vegetation. Aquatic lineages include Hydrachnidia (water mites) in freshwater lentic and lotic systems, springs, and interstitial waters, and Halacaridae in marine habitats. Parasitic forms occupy specialized microhabitats: feather quills (Syringophilidae), hair follicles (Demodicidae), tracheae of honey bees (Tarsonemidae), and skin surface (Trombiculidae larvae). Some species occur in caves.

Cosmopolitan distribution spanning all continents including Antarctica. Individual species and families show varying ranges: Hydrachnidia occur globally in suitable freshwater habitats; Halacaridae are primarily marine; Eriophyoidea and Tetranychidae are widespread agricultural pests with distributions following host plants; host-specific parasites such as Syringophilidae track their avian host distributions.

Activity patterns vary by life style and climate. Soil-dwelling forms show seasonal fluctuations related to moisture and temperature. Plant-feeding species (Tetranychidae, Eriophyidae) are most active during growing seasons. Trombiculidae larvae (chiggers) show seasonal peaks typically in summer months in temperate regions. Water mites (Hydrachnidia) often display life cycles synchronized with host insect availability. Many parasitic forms maintain year-round presence on hosts.

Extremely diverse feeding strategies represented: herbivory (Eriophyoidea, Tetranychidae—plant sap feeding), predation (Smarididae, Bdelloidea, many Anystina—nematodes, other arthropods, smaller mites), parasitism (Trombiculidae larvae on vertebrate skin and lymph; Demodicidae in hair follicles; Syringophilidae in feather quills; Acarapis woodi in honey bee tracheae), fungivory (some soil-dwelling forms piercing fungal hyphae), and microbivory. Some groups switch feeding modes during ontogeny (e.g., Erythraeidae).

• Plants - herbivoreEriophyoidea, Tetranychidae, Tarsonemidae; many are economically significant crop pests
• Birds - parasiteSyringophilidae (quill mites), Harpirhynchidae, Pterygosomatidae; often highly host-specific
• Mammals - parasiteDemodicidae (hair follicles), Trombiculidae larvae (skin), Psorergatidae, Cheyletiellidae
• Reptiles - parasitePterygosomatidae on lizards
• Honey bees - parasiteAcarapis woodi (Tarsonemidae) in tracheae; major apiary pest
• Insects - parasite or predatorPyemotidae parasitize insect larvae; some used in biological control; also prey for predatory Prostigmata
• Nematodes - predatorImportant prey for small soil-dwelling predatory Prostigmata

Development typically includes egg, larva, nymph (often with multiple instars), and adult stages. Larvae usually have six legs; adults have eight legs (except Eriophyoidea with four legs throughout). Trombiculidae exhibit complex life cycles with only larvae parasitic; nymphs and adults are free-living predators. Some Eriophyidae exhibit deutogyny (alternative female morph). Parasitengona show parasitic larval and predatory post-larval life stages. Reproduction is generally sexual, though some groups exhibit parthenogenesis.

Feeding behavior varies dramatically: stylet chelicerae used for piercing plant cells or fungal hyphae; chelate chelicerae for predation; specialized mouthparts for fluid feeding in parasites. Eriophyoidea are generally host-specific to particular plant species or closely related taxa. Syringophilidae females disperse between feathers or hosts while males remain in quills. Some soil-dwelling predators exhibit vertical migration in response to moisture. Pyemotidae have been utilized in biological control programs. Many plant-feeding species cause distinctive damage symptoms including galls, erinea, and leaf bronzing.

Functions span multiple trophic levels: primary consumers (herbivores), secondary consumers (predators), decomposers (microbivores, fungivores), and parasites. Soil-dwelling predators contribute to nematode population regulation. Plant-feeding species can be significant ecosystem engineers through gall formation. Aquatic Hydrachnidia link benthic and pelagic food webs. Parasitic forms influence host fitness and population dynamics. Some species serve as vectors for pathogens (Syringophilidae potentially vector Anaplasma phagocytophilum).

Major agricultural pests: Tetranychidae (spider mites) and Eriophyidae (gall mites) cause substantial crop losses globally. Medical and veterinary importance: Trombiculidae larvae (chiggers) cause dermatitis and transmit scrub typhus in some regions; Demodicidae cause demodicosis; Pyemotidae can trigger allergic reactions. Apiary pest Acarapis woodi threatens honey bee health. Some groups used in biological control (Pyemotidae). Research value: Hydrachnidia serve as bioindicators for freshwater ecosystem health; Prostigmata systematics contributes to understanding Acariformes phylogeny.

• SarcoptiformesFormerly considered at suborder rank alongside Prostigmata; distinguished by lacking prodorsal spiracles and including Oribatida (mite-like, often box-shaped) and Astigmata (including stored product mites and Sarcoptes scabiei)
• ParasitiformesThe other major mite lineage (includes ticks); distinguished by different respiratory systems (tracheae or absence), and typically more uniform body plan with idiosoma and gnathosoma clearly separated
• SphaerolichidaMinor ancient lineage within Trombidiformes; morphology and habits distinct from main Prostigmata radiation

• mites
• Acari
• Trombidiformes
• agricultural pests
• parasites
• predators
• aquatic mites
• medical entomology

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
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