Western Bruce Spanworm
Common NameWestern Bruce Spanworm
Scientific NameOperophtera bruceata
FamilyGeometridae
SubfamilyLarentiinae
Wingspan (mm)28
Primary Colorsgrey, brown, white
HabitatDeciduous and mixed forests, woodlands
Geographic RangeWestern North America (Pacific Northwest, Rocky Mountains)
Host Plantsmaple, oak, birch, apple, alder, willow, aspen
Flight PeriodOctober to November
Flight Stylefluttering
Conservation Statusleast-concern
Lifecycle NotesEggs are laid in the fall and hatch in early spring. Larvae are 'loopers' or 'spanworms' that feed on the leaves of various deciduous trees and shrubs. Pupation occurs in the soil, with adults emerging in late fall.
Identification TipsMales have distinctive mottled grey-brown wings with wavy lines and fly in late fall. Females are flightless with greatly reduced wings, making them appear grub-like.
Description
A small moth with mottled grey and brown forewings, featuring wavy darker lines and lighter patches, giving it a cryptic appearance. The hindwings are typically paler.
