phenModel: A temperature-dependent phenology/voltinism model for a herbivorous insect incorporating facultative diapause and budburst

•Development of a new phenological model for the blue willow beetle, Phratora vulgatissima.•Laboratory data on development times for the blue willow beetle, Phratora vulgatissima.•Model includes a number of options to undertake a sensitivity analysis.•Model can be utilised as a forecasting tool or for climate based simulations.