Determining the control threshold for a pest is common prior to initiating a pest control program; however, previous studies related to the house fly control threshold for a poultry farm are insufficient for determining such a threshold. This study aimed to predict the population changes of house fly population by comparing the intrinsic rate of increase (r_m) for different house fly densities in a simulated system. This study first defined the knee points of a known population growth curve as a control threshold by comparing the r_m of five densities of house flies in a simulated condition. Later, to understand the interactions between the larval and adult populations, the correlation between larval and adult capacity rate (r_c) was studied. The r_m values of 300- and 500-fly densities were significantly higher compared with the r_m values at densities of 50 and 100 flies. This result indicated their representative indices as candidates for a control threshold. The r_c of larval and adult populations were negatively correlated with densities of fewer than 300 flies; this implicated adult populations with fewer than 300 flies as declining while the larval population was growing; therefore, control approaches should focus on the immature stages. The results in the present study suggest a control threshold for house fly populations. Future works should focus on calibrating the threshold indices in field conditions.