The relative diurnal and weekly abundance of the most common natural enemies of the green peach aphid,Myzus persicae(Sulzer, was determined in a potato field in 1977. Two sampling methods were also compared for use in sampling the natural enemies. Groundcloth samples were taken 4 times a day, twice weekly, for 7 wk during the growing season. A natural enemy sampling scheme was developed from the informatlon collected.Coleomegilla maculata(DeGeed adults (Coleoptera: Coccinellidae) and coccinellid larvae were the most abundant green peach aphid natural enemies collected. Linear models significantly explained the relationship between counts forC. maculataadults and degree days, and between counts for coccinellid larvae and degree days. The 0900–1115 period was the least variable sampling period tested for samplingC. maculataadults according to the results of a chi-square analysis on the ranks of the diurnal means. The groundcloth sampling technique was chosen for use in future studies because it is an absolute and non-destructive sampling method, and because it more accurately estimated the size of the larval coccinellid population peak than the other method tested. The between samples variance was the largest component of the variation in the experiment according to a variance component analysis.Coccinellid larvae were aggregated on a stem on 3 of 4 sample dates near the larval population peak according to a chi-square analysis on the variance:mean ratios.C. maculataadults were aggregated on a stem on only the last sample date, when many mating pairs were observed.