Periodicity of Retinia resinella in Northern Europe (Lepidoptera: Tortricidae)
Heliövaara, Karib; Väisänen, Rauno
The periodical appearance of the pine resin gall moth Retinia resinella (Linnaeus 1758) was studied in Finland and Scandinavia mainly on the basis of the galls caused by the larva of the moth. The distribution of the different life-cycle rhythms is preliminarily mapped. In the southern and central parts of the study area the life-cycle of the moth takes 2 years, while at higher latitudes and altitudes the moth shows a regular three-year life-cycle. In the 2-year area the moth flies almost exclusively in even years. A small odd-year population is so far known only from Hanko, southernmost Finland. Odd-year galls have been met more often near the limit of the 2- and 3-year life-cycles. In the 3-year area the 3 allochronic cohorts occur in subequal numbers in an irregular manner.