The house fly, Musca domestica, is an important ectoparasite of goats. House flies develop in and feed upon manure and other nutrient-containing organic matter and may transmit disease causing pathogens associated with these materials. Condensed tannins (CT) are plant secondary compounds that have been found to suppress gastro-intestinal parasites in goats. However, little research has been conducted regarding the effect of CT on ectoparasites such as the house fly. Manure samples were taken from four groups of goats fed alfalfa (Medicago sativa), panicled tick-clover (Desmodium paniculatum), and quebracho (Shinopsis balansae). The goats that were fed alfalfa were split into two groups; goats treated with an intestinal dewormer and those that were not. Five manure samples were taken from each group and inoculated with 50 house fly eggs per sample. Flies were reared and total fly emergence, average daily gain, and average fly weight were measured.