Feeding habits of a little‐known tanypod,Thienemannimyia festiva(Diptera: Chironomidae) were analysed using samples collected from Lough Neagh, Northern Ireland. Amongst a total of 215 individuals examined, a vast majority (90.2%) contained food material in the guts, almost always of animal origin. 91.2% of these feeding predators were observed with chironomid prey, 14,4% with harpapticid copepods and 7.7% with oligochaetes. Numerically, chironomids, harpapticids and oligochaetes accounted for 81.5%, 7.3% and 2.3% of all the prey taken, respectively. The modal number of prey items ingested was two for the fourth instarT. festiva(maximum ten items) and one for the third instars (maximum six items). Among the chironomid prey second and third instars accounted for 43.7% and 40.8% in the fourth instar predators and 78.8% and 6.1% in the third instar predators, respectively. Thus significant differences in diet were observed between the fourth and the third instar predators with respect to the number of prey items and the sizes of chironomid prey ingested.