The Diplogastrids are a heterogeneous group of nematodes regarding morphology and feeding habit. Originally, they live in association with insects: some live inside insects, others live in the tunnels of bark beetles, in cow dung and other food-rich environments, carried there by insects. Diplogastrids have a short generation time and therefore, are able to react rapidly on fluctuations in food availability. In case the microbial activity decreases, they form inactive resting stages, usually called dauerlarvae. The dauerlarvae of aquatic Diplogastrids bear a small oil droplet on their anterior end which allows them to float and get the possibility to find new food resources. Mononchoides striatus, as shown. Is provided of a mouth cavity with small teeth; it occurs in dund and has not been found yet outside Europe.