Insects were collected from the surface of a suburban swimming pool (adjacent to an oak-grassland open space) in northern California over a six-year period (2014–2019). We found 338 morphospecies from 27 families of parasitic Hymenoptera. We note the uncommon taxa found and discuss the species richness of the catch and possible utility of this collection method, comparing our results to the diversity of taxa found, using conventional techniques, in two neighboring sites.