Dispersion indices, including (k) the negative binomial distribution, Green's coefficient of dispersion (C_x ), mean crowding (m* ), Lloyd's (Patchiness index) (m/m*) and variance mean ratio (v/m), were calculated for the populations of two cotton bollworm male moths, Pectinophora gossypiella and Earias insulana, using pheromone traps all-over 2 years (October 95 to Sept. 97) at kaha district, Qalubia Governorate. Comparison showed that: k, C_x and m/m* as well as slopes from regression, all indicated that under the conditions of this test (at densities tested), the populations of the two pests were random. The variance / mean ratio fluctuated considerably more than other indices examined, which, by comparison, appears less reliable than previously thought.