Counts of melanic forms of three species of moth in the Rothamsted Insect Survey light-trap network

Dataset compiled to obtain a broad scale picture of geographical variation in frequency in B. betularia, Odontopera bidentata and Phigalia pilosaria – three species that have shown changes in melanic frequency through time.

Pre-1964 data is from the Rothamsted Barnfield trap which commenced operation in 1933. Post 1964 data is from the Rothamsted Insect Survey light trap network.

melanic_frequencies_totals.csv gives annual counts for each trap. melanic_frequencies_by_form.csv gives annual counts by melanic form (Intermediate, Typical, Melanic) for each trap.