Population studies of the beech leaf mining weevil (Rhynchaenus fagi) in Ireland and Scotland

Abstract. 1. Population budgets for Rhynchaenus fagi, based for the most part on samples of beech leaves taken in June, were constructed for a 10-year period (Northern Ireland) and a 3-year period (Scottish borders).
2. There were years of sustained population growth and sustained decline, but not enough evidence to suggest a cycle. Similar population levels were found at both sites in all but one year.
3. Key factors were associated with the adult stage, although egg mortality may also make a significant contribution to population change.
4. Unknown sources of mortality embodied in the residual mortality were also suspected of acting in a density dependent manner, compensating for variation in parasitism.
5. Death rate of larvae within mines was related to May temperature in Northern Ireland, but not so clearly in Scotland.