A Population Study of the Chironomidae (Diptera) of Lough Neagh

The larval chironomid populations of Lough Neagh were sampled from August 1969 until July 1971. In both years, the average fourth instar larval density was about 4000 m-2 in September/October, and decreased to about 2000 m-2 prior to emergence in the spring. Chironomus anthracinus Zett. was the most abundant species in deep water (> 6 m) with a density of 350 m-2 just before emergence. C. plumosus L. was also present in the same area but at only ten per cent of the numbers. C. cingulatus Meig., found inshore (< 6 m depth), had an average overwintering population of c. 100 m-2. Glyptotendipes larvae formed the most numerous group during the period of study. Pre-emergence populations were 500 m-2 and 1000 mi2 in 1970 and 1971 respectively. The larvae were found in the intermediate zone, mean depth about 4 m. Stictochironomus and Microtendipes both had overwintering larval populations of 100-300 m-2. Stictochironomus larvae were found inshore (< 6 m depth), Microtendipes slightly deeper (< 9 m). Procladius crassinervis Zett., a deep water species, had an average fourth instar density of 300 m-2, but a more complicated population pattern than any of the other species.