New Information on the Biology and Behavior of Atypophthalmus umbratus (Diptera: Limoniidae), a Crane Fly Gradually Spreading throughout the World

The tropical crane fly Atypophthalmus umbratus is gradually being mentioned in new locations around the world, but many aspects of the species′ biology remain unclear. In greenhouses of the Botanical Garden of P. J. Šafárik University in Košice, Slovakia, Atypophthalmus umbratus probably occured since at least 2014 according to photo documentation, with the species identity confirmed by samples taken since 2018. More detailed data on 125 adults were obtained using various monitoring methods in the years 2014 – 2023. This fly, mostly rarely seen during the year, can occasionally be very numerous. Its abundance is probably related to the occurrence of predators, to the frequency of changing the substrate and to different regimes of biological or chemical control against pests, which is specific for individual greenhouses. Adult insects have been observed resting on flower pots or greenhouse surfaces, feeding on various plant or animal excreta, and being caught as prey by spiders or insectivorous plants. Despite previously published assumptions about the development of larvae among algae in the aquatic environment, some imagoes in this study were captured after rearing from soil substrate samples from potted plants. In two trials with capturing hatched imagoes, the counted ratios were 120 - 130 individuals per 1 m2, or 630 - 1300 individuals per 1 m3 of substrate in flowerpots. The imagoes gradually flew out of from the substrate samples over the course of more than 3 months, so it seems that the preimaginal stages of A. umbratus can persist in the soil for a long time and can be easily transported, e.g. just with potted plants. Two larvae feeding on dead organic matter were directly observed. These records would explain the wide distribution of this species not only in the tropics and subtropics, but also the distant isolated occurrences in greenhouses at higher latitudes.