Influence of flooding on terrestrial chironomids in grassland (Diptera: Chironomidae) Although flooding is an important factor for the invertebrate fauna of grassland, not much is published on this topic. As in other groups the different species of terrestrial Chironomidae display different reactions during flooding. Some larvae will move to drier parts, others remain on the spot. All species can survive for some time submerged in water, but the uptake of water can be a problem, especially in summer time. Some species are more or less characteristic for very wet grassland (like Metriocnemus tristellus), but nearly all species depend on the presence of drier parts of the grassland for maintenance of the population.