The seasonal distributions and biology of four species of billbug on New Jersey turfs during 1986 and 1987 were examined;Sphenophorus parvulusGyllenhal, a common pest of turfgrass, and three additional species,S. venatuss.l. (Say),S. minimusHart, andS. inaequalis(Say), that had previously been overlooked as pests of cool-season turfgrasses in New Jersey. Linear pitfall trap collections of adults indicated: (1) a nearly equal overall abundance of the four species, (2) greater activity ofS. inaequalisin the early spring and autumn, and (3) continued activity ofS. venatusthrough the summer. The abundance ofS. venatusadults throughout the summer, and continuous egg laying of all four species through August suggested a partial second generation. Larvae of all four species were found damaging cool-season turfgrasses during July. Laboratory-rearing work found little difference in the number of days for egg hatching and pupation, but a longer larval period forS. venatus. To facilitate identification and study by turfgrass specialists, an illustrated key to eight known billbug turf pests is provided and their geographic distributions in the United States are reviewed.