Semi-social
Guides
Ambrosiodmus tachygraphus
Ambrosiodmus tachygraphus is a North American ambrosia beetle described by Hopkins in 1915. Like other members of the genus Ambrosiodmus, it engages in obligate mutualism with fungal symbionts, specifically the wood-decaying fungus Flavodon ambrosius. This partnership enables the beetle to colonize and reproduce in dead or dying wood by farming fungi that digest cellulose and lignin, converting wood into nutritious food for beetle larvae and adults. The species is part of a group known for forming semi-social colonies with thousands of individuals, facilitated by their unique ability to cultivate a true wood-degrading fungus rather than merely extracting readily available nutrients from freshly dead tissues.
Philoponella oweni
Philoponella oweni is a small cribellate orb-weaver spider (4.7–7.1 mm) found in arid regions of the southwestern United States and northwestern Mexico. The species exhibits facultative semi-social behavior, with females living either solitarily or in communal groups of 2–40 individuals depending on web-site availability and prey abundance. Despite communal living, individuals do not cooperate in prey capture, web construction, or brood care. Communal females benefit from higher feeding rates and greater egg production, but suffer increased parasitism by pteromalid wasps, resulting in equivalent net reproductive success between strategies.