kleptoparasitic and predatory; feeds on pollen in bee nests and can attack and kill developing bees

Name and classification

Chaetodactylus Rondani, 1866

Superorder Acariformes » Order Sarcoptiformes » Suborder Oribatida » Infraorder Desmonomata » Hyporder Astigmata » Family Chaetodactylidae » Genus Chaetodactylus

Type species
Trichodactylus osmiae Dufour, 1839

Common synonyms
Trichodactylus, Trichotarsus

Common names
hairy-footed mites, pollen mites


Phoretic deutonymph: Gnathosomal solenidion present, setae on free palpi absent, and free palpi present (Fig. 13).

Immobile deutonymph: present (Fig 4)

Female: Sternum present and fused to epigynum (=progenital sclerite, i.e., unpaired sclerite situated anterior to the oviporus) (Fig. 6).

Homeomorphic male: Progenital sclerites completely fused, forming large unpaired sclerite (Fig. 14). Lateral processes (horns) of dorsal supporting sclerite with secondary processes (Fig. 14). Distinct anterodorsal protuberance on tarsi I-IV present (Fig. 15).

Heteromorphic male: absent


Worldwide (except Antarctica)

Bee hosts

family Megachilidae: tribes Lithurgini (Lithurgus, Trichothurgus, and Microthurge), Osmiini (Osmia, Hoplitis, and Chelostoma), Anthidiini (Rhodanthidium and Anthidium), and Megachilini (Megachile)

family Apidae: tribes Emphorini (Melitoma, Diadasia, Ptilothrix, and Ancyloscelis), and Tapinotaspidini (Chalepogenus)

Most species occur on Osmia and Lithurgus, while only a single species is associated with each of the remaining host genera.

Host association level


associated exclusively with bees or their close relative, wasps; cannot live without these hosts


some life stages are associated with bees, while others are not

Facultative or opportunistic

can complete entire life cycle without bees or their close relative, wasps


Host associations, feeding, and dispersal

  • Feeding stages live in bee nests (Fig. 18). They are mostly kleptoparasitic, but they may kill developing bee larvae via direct attack.
  • Phoretic deutonymphs (non-feeding stage) disperse from one nest to another on adult bees (Figs. 16, 17). They cause no direct harm, but large mite loads may affect the bee's flying abilities and survival. In managed and aggregated bee colonies, they may infect new nests by active dispersal (walking).
  • Non-phoretic deutonymphs (non-feeding stage) can survive in the nest cavity to infest new bee generations, if the same nest is reused.


These mites usually kill young bee larvae and feed on provisioned pollen and nectar. In nests with partitions (Osmia), bees that develop in the innermost cells chew their way out of the nest, and phoretic deutonymphs from the opened cells may attach to them. The mites in the innermost cell may die because of their inability to break through the partition. In nests without partitions (Lithurgus), some young bees may complete development and transform to adults that disperse the mites.

In colonies of Osmia cornifrons managed for pollination of blueberries in the USA, Ch. krombeini phoretic deutonymphs could disperse from a nest to nearby nests by walking through nest entrances and holes made by parasitic wasps. Cross-nest dispersal via blueberry flowers visited by multiple individuals of O. cornifrons was proven to be negligible (Park et al., 2009).

The presence of the inert non-phoretic deutonymph along with the phoretic deutonymph is the most conspicuous feature in the life-cycle of this genus. The inert deutonymph is a highly regressive, cyst-like morph with legs and most setae greatly reduced (Fig. 4). It is capable of surviving in old bee nests and infesting new hosts that reuse these nests or the nest material. When mites are trapped in the innermost cells of an infested nest or all bee larvae are killed and therefore cannot transfer mites to a new nest as adults, inert deutonymphs can be very important for mite survival.

Biology has been studied for Chaetodactylus osmiae (Chmielewski, 1993; Fain, 1966; Lith, 1957; Popovici-Baznosanu, 1913), Ch. birulai (Lith, 1957), and Ch. krombeini (Krombein, 1962, 1967).