Phenology of the common earwig Forficula auricularia L. (Dermaptera: Forficulidae) in an apple orchard

Observational data taken over 13 years, on the phenology and the abundance of the first brood of the common earwig, Forficula auricularia L., in a Dutch apple orchard were analysed. The results are used to indicate a fixed sampling moment for this predator. The fourth instar nymphs emerged between 12 June and 10 July, and the adult stage was reached between 8 and 30 July. The observed phenology, and the number of earwigs in shelter traps, correlated well with the temperature sum in day-degrees above a thermal threshold of 6 C, accumulated from 1 January. Maximum numbers of earwigs could be trapped in the trees when the nymphs of the first brood entered the fourth instar, generally between 600 and 750 day-degrees.