Presocial or Subsocial Behavior: Such behavior is known in Bledius and Platystethus (Oxytelinae) and Eumicrota (Aleocharinae). Adults construct chambers in which they deposit and guard their eggs and young, Bledius in sandy or muddy shores, Platystethus in the dung of ungulates, and Eumicrota in mushrooms.
Relationships with Social and Communal Insects: Another dimension of social behavior has arisen in interactions with termites and ants -- thousands of species of Aleocharinae, and many species of several other subfamilies, are inquilines in the nests of these social insects, some with bizarre structural and behavioral adaptation. Emus (Staphylininae) invades bee nests in Europe, and a species of Euvira (Aleocharinae) develops in communal nests of a butterfly in Central America.
Relationships with Higher Plants: Adults of some Omaliinae are attracted to flowers, and some of these have been demonstrated to pollinate the flowers. An example is Pelecomalium testaceum (Mannerheim) (Omaliinae), which pollinates Lysichiton americanum Hultén & St. John (Araceae) in the mountains of the Pacific coast of the USA and Canada. It is conceivable that Polyobus spp. (Aleocharinae) do the same for Espeletia spp. (Asteraceae) in the northern Andes of South America. Charoxus spp. (Aleocharinae) have a different, but yet highly specialized obligate relationship with plants -- the adults are attracted in the Neotropical region to the syconia of Ficus spp. (Moraceae) within which they oviposit, but the adults and larvae feed on pollinating wasps (Agaonidae) of those fig flowers.
Relationships with Fungi: There are three forms of relationships with fungi. Adults and larvae of many species eat fungi. Others find prey items (fly larvae and other organisms) in fungi. A major association with fungi is that adults of many species are infected by Laboulbeniales (Ascomycetes) and some other fungi, many of which specialize at the level of host genus, tribe, or subfamily.
Relationships with Decomposing Plants, Dung, and Carrion: The frequent presence of staphylinids at decaying plant materials raises the question of whether they arrived there by random movement, and then remained there, or whether they are attracted in much the same way that adults of their prey (fly larvae, etc.) arrived there. Thus, adults and larvae of Cafius (Staphylininae) inhabit decaying brown algae (Fucales [kelp or wrack]) on sea beaches and eat fly larvae; adults and larvae of some Philonthus (Staphylininae) occur in dung of ungulates and eat fly eggs and larvae; adults of some Eulissus (Staphylininae) occur in dung of ungulates and there maim, then eat, adult scarab beetles; adults and larvae of some Belonuchus and Philothalpus (Staphylininae) occur in decaying fruits, and eat fly larvae; adults of some Platydracus (Staphylininae) occur in carrion and eat fly larvae and adults.
Relationships with Terrestrial Molluscs: Some staphylinids have been shown to feed occasionally on slugs and snails, although apparently they are not specialized to do so as are Cychrini (Coleoptera: Carabidae), nor have slugs and snails been shown to be an important part of the diet as in some Silphinae (Coleoptera: Silphidae). However, a strange, almost commensal relationship with snails has evolved in some Asian Aleocharinae such as Zyras sagax Cameron, in which the adult beetles enter the mantle cavity of Ryssota (Gastropoda: Helicarionidae) and perhaps feed on mucus or feces of the snail.
Nests of Vertebrates: Some staphylinid species have specialized to live in the nests of vertebrates, especially tortoises, birds, and rodents. Their prey seems to be mainly the larvae of fleas and flies. In Florida (USA) where populations of the tortoise Gopherus polyphemus (Daudin) (Testudines: Testudinidae) are declining through habitat loss and disease, populations of the staphylinid inhabitants of its nests also must be declining. Names of species of Staphylinidae found in birds' nests were compiled almost 40 years ago, but there is little information on their behavior. In central Asia, where sylvatic plague is endemic, some staphylinids are credited with suppressing flea populations, and thus help to suppress transmission of plague. Adults of Amblyopinus and close relatives (subtribe Amblyopinina of subfamily Staphylininae) occur in the fur of some rodents in Central and South America. For years they were suspected of being parasites of these rodents, and taking blood from them. Now, however, they are believed to be phoretic on the rodents, thus being transported from nest to nest. They oviposit in the nests, and larvae feed as predators there of other arthropods.