Emergencetime and period of chironomid midges occurrlng from an indoor drainage

Mass emergence ofchironomidmidges often leads to severe nuisance conditions in food industries. We tried to clarifythe seasonal abundance and the emergence time of chironomids caught by a light traps in this industry. A total of38,708 chironomids was collected duringthe study period, andthe largest number of adult was recorded in fall. In addition, some chironomids were collected even in thewinter. These results suggest that air temperate in winter at this industry is highenough for emergence of chironomids.Asfbr emergence time,the number of chironomids increased around dawn and dusk,and decreased in the day and night. The results of the present study would be useful information for drafting planto prevent outbreaks of nuisancemidges from indoor sewage drain.Article信州大学山地水環境教育研究センター研究報告 6: 109-114(2010)departmental bulletin pape