Operophtera brumata

(Linnaeus, 1758)
Winter Moth

Sort #: 1757 | P3 #: 910281 | MPG #: 7436
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Larval substrate: Various deciduous trees; Quercus* (Oak), Malus* (Apple)
Phenology: Adult: 11/01 to 12/28 (134 records)

Comment: It is not clear exactly when this introduced species found its way to Masschusetts, but it was probably sometime in the 1990s. Its presence was however confirmed only in 2003. It still seems to be restricted to the Eastern half of the State. The species is very difficult to separate from the native O. bruceata (Bruce Spanworm) without resorting to male genitalia dissection or DNA amalysis. The hindwing of O. bruceata tends to have a central spot, although this character is apparently unreliable (those without a spot can be either species). Female Winter Moth tend to have clearly visible small 'wings', but in the Bruce Spanworm females the wings are very strongly reduced. Winter Moth are said to emerge a little later than Bruce Spanworm, towards the end of November. However, in Britain, Winter Moth can fly from mid-October and even into February and some very Winter Moth-like individuals have been reported in Massachusetts from the beginning of November. This needs to be investigated further. It is unlikely that all records in the database of the two species are 100% correct.

Status in MA (automated assessment): Fairly widespread, common
Status in N. America: Introduced
MA Endangered Species Act status: None
First Year Reported: 2004
Last Year Reported: 2023

Distribution by County: Worcester, Middlesex, Essex, Suffolk, Norfolk, Bristol, Plymouth, Barnstable, Dukes, Nantucket
Number of Records: 173