Musca domestica Linnaeus or house fly is one of the well-known cosmopolitan
pests. Poultry farms, horse stables and ranches are some of the main habitats for house flies
to extend their interference and disturbance. Since 1999, large number of fly population
around horse stables and barns in Terengganu Equestrian Resort (TER) was detected and still
persists till today. Imported horse food are speculated to be the main cause for the increasing
number of these flies. The current study was conducted to determine the effect of imported
horse food (i.e. chaff, pallet and alfalfa) and the food conditions (wet and dry) on house fly
population densities. Commercial sticky papers were used for trapping house fly distribution
around the horse stables and barns in TER from October 2013 to January 2014. A total of
36,751 flies were caught during the eight week study period. The highest number of flies
(2,843 individuals) was caught when using ‘wet alfalfa + chaff’ whereas the lowest catch was
when using ‘dry alfalfa’ (1,652 individuals). Generally, the wet food treatments captured
higher flies compared to dry food treatments. The total number of captured flies was found to
be influenced by relative humidity. Higher mean number of flies was captured during lower
weekly humidity. Our findings conclude that the wet condition of imported horse food in TER
increases the house flies population densities. Thus, urgent action should be taken as soon as
possible and may need special management considerations in order to reduce the impact of
house flies on the horse industry in Malaysia.