Adela septentrionella is a moth of the family Adelidae or fairy longhorn moths. It was described by Walsingham in 1880. It is widespread from southern British Columbia and north-western Idaho to the Transverse Range in southern California.
The length of the forewings is 4.5–5.7 mm.[1] Adults are on wing from mid April to mid July.[2]
The larvae feed on buds of Holodiscus discolor. Pupation takes place in late March or April.