Diamondback moth (DBM) (Plutella xylostella (L.» insecticide efficacy and population dynamics studies were conducted in 51. Kitts 1985 1987. Experiment station and "on-farm" trials were conducted in addition to monitoring small farmers cabbage crops for DBM and Apanteles plutellae population levels. Pennethrin, Bacillus' thuringiensis (Berliner), and pirimiphos-methyl, controlled DaM adequately. Peaks in A. plutellae parasitism coincided with a predominance of 4th instar larvae. The presence of high parasite populations delayed the time to first spray. A relative growth rate analysis of DBM populations indicated that growth rates are correlated to percent A. plutellae parasitism. It is hypothesized that parasitism levels exceeding 25-35% may control DBM populations.