Rare immigrant. Recent resident.
This is the Victorian collector's classic all-time favourite, often named the 'Blue Underwing'.
Up until recently all modern-day Norfolk records were of assumed migrants, recorded mainly along the coast, usually in late August - September. It is now thought to be resident.
According to Heath (MBGBI V.10, 1983), in around 1935 C. fraxini is believed to have been resident for some years in north Norfolk, but its occurrence there is not documented. Other publications including Skinner (MBI,1984) mention it as being resident in the Norfolk Broads from the early to mid 1930s. In the New Naturalist edition: The Broads 1965, Ted Ellis notes it as possibly breeding in the district occasionally ( e.g. on poplars near Barton Broad, where the moths appeared annually in fair numbers for several years in succession in the 1930s). The original source of this information is unfortunately unknown, and we have no C. fraxini records from Barton Broad or the 1930s.
In 1976 a remarkable seven specimens were recorded in Norfolk, a very rare occurrence in the UK at the time. It was not recorded in large numbers again until 2019, when ten confirmed and one unconfirmed were recorded, the most ever in Norfolk on record in a single year. In 2020 this record was smashed with 31 (to date) adults recorded across Norfolk. The species is now thought to be breeding once again in Suffolk, and with huge numbers recorded recently, it appears to be locally breeding again(?) in Norfolk. [JW]
The larvae are nocturnal canopy feeders on mature Populus spp. and Aspen and are seldom seen, being out of reach to recorders.
Records of immaculate specimens seen before the end of August are questionable as this species is often captive bred.
Please note records will not be accepted without confirmation. Photo preferably showing the blue underwing required.
|Retained Specimen / Photograph will be Required. |
Recorded in 50 (68%) of 74 10k Squares.
First Recorded in 1834.
Last Recorded in 2021.