As a result of publicity over the presence of adult midges causing a nuisance to households, and the environmental concerns on the use of organophosphates, a series of trials were carried out from 1989 to 1992 in the laboratory and in the field to evaluate the efficacy of cyromazine. Cyromazine, discovered and developed by Ciba-Geigy, is a substituted melamine chemically related to the triazine group. Cyromazine acts by interrupting the life cycle around the time of egg hatch or by interfering with moulting and puparium formation due to induced morphological aberrations. The subsequent emergence of adults is suppressed or incomplete.
Application is most effective against young larvae where it acts as a stomach poison.
At higher concentrations and against older larvae it also displays contact activity. The two pot trials consisted of three replicates of 5-10 field collected, mixed aged chironomidae larvae per pot. Ninety cm 3 of sieved sludge collected from the oxidation ponds was placed in the bottom of each pot as a habitat for the larvae. Water, again taken from the oxidation ponds, was put in to a depth of 5 cm. The tops were covered with nylon mesh to retain any emerging adult midges.