Field evidence of caddisfly larvae (Trichoptera: Limnephilidae, Leptoceridae) using alien Crassula helmsii (Kirk) Cockayne fragments (Saxifragales: Crassulaceae) in case construction.

We present the first field observations of caddisfly (Trichoptera) larvae using an invasive alien aquatic plant, Crassula helmsii (Kirk) Cockayne, in case construction. In samples from invaded ponds across the UK and Belgium, we have recorded the presence of C. helmsii fragments in cases from Limnephiluslunatus Curtis, 1834, Limnephilus marmoratus Curtis, 1834, Limnephilus flavicornis (Fabricius, 1787) (Limnephilidae), Triaenodes bicolor (Curtis, 1834), and Oecetis furva (Rambur, 1842) (Leptoceridae). Fragmentation of C. helmsii in case creation and augmentation may produce vegetative propagules, thus facilitating further dispersal of this invasive macrophyte. [ABSTRACT FROM AUTHOR]