The solitary parasitoid Pseudavga flavicoxa has been reared, in some numbers, from cocoons of the bucculatricid moth Bucculatrix thoracella collected as larvae descending from Tilia × vulgaris to form their cocoons, at Jealott’s Hill, Berkshire, England. The taxonomic confusions and complications bedevilling its determination are outlined, and the recognition of the genus Pseudavga Tobias, 1964 is proposed. Egg placement in this koinobiont ectoparasitoid and the related genus Rhysipolis is discussed.