Prediction of the emergence period for overwintering chironomid larvae (Diptera: Chironomidae) at the lower reaches of the Kiso River, Central Japan

Species composition and period of emergence were investigated for overwintering Chironomidae at the lower reaches of the Kiso River by rearing larvae to obtain fundamental information for drafting a plan to prevent outbreaks of nuisance midges. Adults of 9 species emerged from the substrate samples in February 2006. The four most abundant species, Stictochironomus akizukii, Hydrobaenus kondoi, Tanytarsus takahashii and Einfeldia dissidens, occupied 88.0% of the total abundance. Using effective accumulative temperature for emergence and in situ water temperatures, the in situ emergence periods of the overwintering generation in 2006 were predicted as until early March for H. kondoi, from the end of March to early May for S. akizukii and T. takahashii, and late April to mid-June for E. dissidens.