Control of Chironomid Flies Breeding in Sewage Filters

Abstract

The literature concerning the identification, habits and control methods of common sewage filter flies has been reviewed with special reference to the chironomid Metriocnemus hyaropetricus (Kieff.) which was the nuisance species breeding on the filters at Tamworth. References have been given for the identification of larval and adult stages of filter flies, the habits of flies in relation to varying filter operation methods and basic physica! variables such as light and temperature, and the various chemical and operational methods of fly control used in the past. Other literature concerning general filter ecology and relations between members of filter fauna has been reviewed. The methods used for sampling filters for film, microfauna and macrofauna, together with the various methods of fly trapping and toxicity testing have been described. Methods have been developed for culturing certain filter insects. The results from this project can be summarised as follows. The insecticide (Actellic M20) has been applied to filters and has controlled M.hygropetricus. The success of this method is limited when factors such as timing of dose, financing a sampling programme and resistance are considered. The insecticide has been found to effect other common filter fauna at various concentrations. Resistance to the insecticide by M.hygropetricus after 3 years of treatment has been suggested. Certain operational modifications applied to filters have controlled M.hygropetricus and it is considered that these methods are preferable to insecticidal methods on an ecological and financial basis. Using laboratory scale filters the specific habits of M.hygropetricus and Psychoda alternata Say have been identified and competition between these species has been proved which has important implications when considering the control mechanisms of the operational modifications. Miscellaneous findings have included the following. Diurnal emergence patterns have been found with M.hygropetricus, and Psychoda severini Tonn., also it has been found possible to culture M.hygropetricus, P.severini and P.alternata from eggs to adults allowing investigation of the various life cycle stages. been reviewed.