The pea leaf weevil (Sitona lineatus L.) is an important pest of peas in the northwestern USA. Tillage regime may influence abundance of this pest. To evaluate pea leaf weevil activity-density under different tillage practices, pitfall trap sampling was conducted throughout the growing season during 2000-2002 at the University of Idaho Kambitsch Farm and in growers fields. Results show pea leaf weevil activity-density to be over five times greater in CT (conventional tillage) than in NT (no till) fields over the growing season. The lower relative abundance in NT fields could be due to the coincidence of earlier crop emergence in CT with weevil immigration, reduced weevil activity in NT due to greater plant residue and/or micro-climate variations in these fields, increased mortality in NT from predation, or a combination of these factors. To evaluate absolute abundance and seedling damage, linear-foot-of-row soil samples were taken at Kambitsch, in 2003. Pea leaf weevils were significantly more abundant in CT than NT pea plots, as was damage. To evaluate pitfall trap capture efficiency (CE), marked weevils were released and recaptured in cages in both tillage types. Trap CE for the weevils were not significantly different between tillage treatments, thus differences in activity density show actual differences in relative abundance.