SUMMARYTraps containing a sex attractant of the pea moth (Cydia nigricana) were used to monitor numbers of male moths in individual fields in south‐eastern and eastern England from 1976 to 1978 at 16 or more sites/yr. Data concerning catches at different sites on several occasions over the flight season, and dates on which a ‘threshold catch’ was achieved were examined, and were related weakly to site locations within areas. Area spray warnings, based on trap catches at a few sites within a large area, provide a less reliable indication of the need to spray than on‐site monitoring (two traps) in each pea field. On‐site monitoring may be improved by specialist interpretation of tra