Estimation of the numbers of flies reoccupying substrates were made at set time intervals post-treatment by an experienced technician. Environmental conditions from the beginning to end of the tests (eg, precipitation, wind speed and ambient air temperature) were noted. Observations were conducted for a minimum of 72 hours post-spray. Individual test substrates were not test replicated as we noted earlier ( Mulla and Chansang, 2007) that the eye flies had heterogeneous temporal and spatial distributional patterns.