A mark-recapture methodology is presented for quantifying dispersal parameters for small hymenopteran parasitoids. Results of studies using this methodology are presented for the egg parasitoid Anagrus epos (Hymenoptera: Mymaridae) dispersing in grape vineyards in California. A. epos was found to exhibit some upwind displacement in all three mark-recapture trials and strong directional upwind displacement in one of the trials. A preliminary estimate of 520 m(2)/day is suggested for the diffusion rate of A. epos in mid-summer at high host densities. The high mobility and directionality exhibited by this parasitoid support concerns regarding dispersal of biocontrol agents away from target areas following augmentative releases. Application of this methodology to other small parasitoids should be feasible and will contribute to effective augmentative biological control. (C) 1996 Academic Press, Inc.