neutral or beneficial; habitat generalists that feed on microarthropods and fungi

Name and classification

Lasioseius Berlese, 1916

Superorder Parasitiformes » Order Mesostigmata » Suborder Monogynaspida » Hyporder Dermanyssiae » Family Blattisociidae » Genus Lasioseius

Type species
Seius musicatus [lapsus pro muricatus] Berlese, 1887 (non Koch, 1839) (=Typhlodromus berlesei Oudemans, 1938)


Female: Dorsal shield undivided and without midlateral incisions (Figs. 1). In most species, sternal shield with 3 pairs of setae: st1, st2, st3 (Fig. 3); st4 situated on metasternal shields (Figs. 3). Ventrianal shield wide, bearing 2 or more pairs of ventral setae (JV and ZV), in addition to the three circumanal setae (Fig. 5). Paranal setae inserted anterior to hind margin of anus (Fig. 5). Peritrematic shield broadly connected to exopodal plate, curving behind coxa IV (Fig. 7). Peritrematic shield clearly wider than diameter of stigma at level of stigma (Fig. 7). Corniculi widely separated (Figs. 8, 9). Fixed digit with filiform pilus dentilis (Fig. 11 ). Tectum convex or triramous (Fig. 12). Median lobe of pulvillus (membranous, pad-like structure) of legs II-IV rounded (Fig. 13).


Worldwide; found in association with bees in the Palaearctic, Nearctic, Oriental, and Australasian regions.

Bee hosts

found in nests of honey bees (Apis) and bumble bees (Bombus)

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

  • All stages are probably predatory on microarthropods in different habitats, including honey bee hives and bumble bee nests. Some species are omnivorous (both predatory and fungivorous).
  • Mites also probably enter bee nests by walking if a nest is nearby.


Lasioseius is a morphologically diverse genus, with more than 100 described species found on rotting organic substances, under bark, and in forest litter, moss, soil, nests of small mammals and birds, bracket-fungi, tree-holes, stored products, warehouses, and hay. Some species are omnivorous, feeding on microarthropods and on fungi, while others are only predatory (Enkegaard and Brodsgaard, 2000; Walter and Lindquist, 1989). Several species have been collected in beehives. Among them, one species, Lasioseius penicilliger, has also been found in bumble bee nests. These species are habitat generalists and probably do not have a particular preference for bee nests.