Astigmata

Distinguished from other Sarcoptiformes by the complete absence of stigmata and tracheae; respiratory exchange occurs through the cuticle. Separated from Endeostigmata and Oribatida by the combination of soft body, reduced setation, and typically five active life stages (egg, larva, protonymph, deutonymph, tritonymph, adult) rather than six. The presence of a hypopial deutonymph stage is diagnostic for many lineages, though lost in some derived groups such as most feather mites and certain Winterschmidtiidae. Within Astigmata, feather mites (superfamilies Analgoidea, Pterolichoidea, Freyanoidea) are recognized by permanent association with avian hosts and corresponding morphological specializations for feather gripping.

Diverse: permanent ectosymbionts on bird feathers (flight feathers, contour feathers, down); nests of birds, mammals, and insects; decaying organic matter including leaf litter, compost, rotting wood, and fungal substrates; stored food products and commodities; soil habitats; marine and estuarine rocky shores (Hyadesiidae); and as parasites or commensals on mammalian skin and respiratory tracts.

Cosmopolitan. Feather mites occur globally wherever birds are present, with distributions tracking host ranges. Soil-inhabiting and stored product lineages occur across all continents, with some genera (e.g., Tyrophagus, Histiogaster) showing nearly worldwide distribution through human commerce. Specific distributions vary by family and ecological guild.

Year-round activity for permanent feather mite residents on birds. Soil and decaying matter inhabitants show seasonal peaks correlated with moisture and temperature; many temperate species exhibit winter diapause as hypopial deutonymphs. Stored product mites active year-round in controlled environments, with population fluctuations following humidity and temperature changes.

Highly variable by lineage: feather mites consume feather keratin, skin debris, uropygial gland secretions, fungi, and bacteria; soil and stored product mites feed on fungi, decaying plant matter, and microorganisms; some lineages are predatory or parasitic. Specific diet components often poorly documented for individual species.

• birds (Aves) - permanent ectosymbiontPrimary hosts for feather mites (Analgoidea, Pterolichoidea, Freyanoidea); mites complete entire life cycle on host
• mammals (Mammalia) - parasite or commensalSkin parasites (e.g., Sarcoptidae causing scabies) and respiratory tract inhabitants (Kytoditidae)
• arthropods - phoretic or parasiticHypopial deutonymphs attach to insects and other arthropods for dispersal; some histiostomatids associated with harvestmen and other arthropods
• insect nests - inhabitantMany Winterschmidtiidae and related families in nests of bees, wasps, ants, and termites

Typically includes five immature stages: egg, larva, protonymph, deutonymph, and tritonymph, followed by adult. Many lineages possess a heteromorphic deutonymph (hypopus) specialized for dispersal—non-feeding, with regressed mouthparts and ventral sucker plates for attachment to arthropod hosts. Feather mites and some other derived groups have lost the hypopial stage, completing all stages on a permanent host. Development time varies from days to months depending on temperature and lineage; some temperate species show extended lifespans with winter diapause.

Feather mites exhibit microhabitat specialization, with different species occupying distinct feather regions (vane, barbs, calamus) and avoiding competition through spatial partitioning. Phoretic behavior in hypopial stages involves active seeking and attachment to arthropod carriers. Some soil-dwelling lineages show aggregation behavior around fungal resources. Host specificity is generally high in feather mites, with phylogenetic tracking of avian hosts; horizontal transmission occurs primarily during host body contact.

Feather mites likely contribute to feather maintenance by removing debris, fungi, and excess oils, potentially benefiting host condition; at high densities, some species may cause damage. Soil and decomposer lineages participate in nutrient cycling and fungal decomposition. Stored product mites act as contaminants and spoilage agents. Some lineages are significant parasites (e.g., Sarcoptes scabiei causing mange in mammals).

Medical: Sarcoptes scabiei causes scabies in humans, a significant parasitic disease. Agricultural: stored product mites contaminate food and feed, causing economic losses and allergic reactions; some species (e.g., Tyrophagus, Acarus) are major pests of stored grains, flour, and other commodities. Veterinary: various species parasitize domestic animals. Scientific: important model organisms for studying host-parasite coevolution, particularly feather mite-avian systems; some lineages used in studies of dispersal biology and life cycle evolution.

• OribatidaBoth are suborders of Sarcoptiformes, but Oribatida possess stigmata, heavily sclerotized bodies, and typically six active life stages; Astigmata are soft-bodied, apneustic, and have five stages with hypopial specialization in many lineages.
• EndeostigmataShares apneustic condition, but Endeostigmata are generally more primitive with six life stages and different gnathosomal structure; Astigmata are more derived with specialized life cycles and often reduced mouthparts.

• mites
• acari
• feather mites
• stored product pests
• scabies
• phoresy
• hypopus
• avian symbionts

• BugGuide
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Cosmetid harvestman with parasitic/phoretic mites in Argentina | Beetles In The Bush
• Feather Mites (Acari: Astigmata): Ecology, Behavior, and Evolution
• Revision of Tyroborus Oudemans, 1924 (Acari: Astigmata: Acaridae)
• Taxonomy and distribution of sarcoptiform mites (Cryptostigmata and Astigmata: Acari) in South Australian soils
• A survey of lifespan in Winterschmidtiidae (Sarcoptiformes: Astigmata)
• A survey of lifespans in Oribatida excluding Astigmata (Acari)
• An exceptionally well-preserved Eocene fossil mite, Histiogaster altilis sp. n. (Acari: Astigmata), from tree sap: Evidence of morphological and ecological niche conservatism, with a review of fossil Astigmata
• Prelude to a study of the feather mites of Australia (Acariformes: Astigmata)
• Systematic revision of the feather mite genus Protolichus Trouessart, 1884 (Astigmata, Pterolichidae)
• Population biology of a phytophagous mite of marine and estuarine rocky shores (Astigmata, Hyadesiidae)
• Phylogeny and host-parasite associations of feather mites of the Pteroherpus generic group (Astigmata: Pteronyssidae)
• Food competition and feeding behavior and its implications for the phylogeny of the Histiostomatidae (Astigmata)
• Acari Astigmata (excluding Feather Mites) parasitic on Australian vertebrates: an annotated checklist, keys and bibliography
• Contributions to the feather mite fauna (Acariformes: Astigmata) of birds (Aves) in Türkiye