Dark Crimson Underwing Catocala sponsa

Until Dave Norgate found one at Toftwood in 2018 this species was not known in Norfolk except for 2-3 old unconfirmed records. In the next few years Dave continued to catch them annually and others found them elsewhere in the county, especially in the Norwich area. Multiple records from the same site over different years strongly suggests breeding taking place locally but other records may be migrants or individuals dispersing from elsewhere in southern England.

This one was my first. It was more obviously different from Red Underwing Catocala nupta than I had imagined. The "crimson" of the hindwings is much pinker than on Red Underwing and of course the upper forewings are much darker. The pattern of the black stripe through the hindwing clinches the ID but I'm not sure it's essential to see this. Having said that it's also helpful in eliminating other rarer Catocala including Light Crimson Underwing Catocala promissa, although that's normally paler and greyer.

Dark Crimson Underwing Catocala sponsa, North Elmham (Norfolk, UK), 13th August 2024