The relative efficiency of the D-Vac® suction insect collector as a sampling method for collection of potato leafhopper adults on alfalfa was compared with that of an emergence trap, drop trap, and sweep net. The D-Vac and drop trap techniques were most efficient. Using the D-Vac insect collector, a sampling plan was developed to study the dynamics of potato leafhopper populations on alfalfa. The sample unit was a set of 10 (0.09 m2) sucks (a suck consisted of placing the suction orifice on the soil for ca. 2 sec). This sample unit showed the distribution of leafhoppers to be aggregated, following the negative binomial distribution. This distribution was used to calculate sample sizes required to estimate adult density within either a 10, 20, or 30% coefficient of variation. The densities of adult leafhoppers during most of the 1976 and 1977 seasons permitted population estimates within a 10–20% coefficient of variation.