Bug FAQBrown-lined Looper
Neoalcis californiaria · Order: Lepidoptera · Family: Geometridae
Also called: Brown-lined Looper Moth
The Brown-lined Looper is a moth with a wingspan of about 34 mm and three dark lines on each wing. Its larvae are inchworm-like caterpillars that feed on Douglas fir and other conifers, overwinter as mid-instar larvae and become adults from June to November.
Source: Wikipedia
How to recognize it
Three dark transverse lines on each wing and scalloped hindwing edges identify this species. The ground colour varies from ashy gray to light or dark brown with many brown speckles and darker patches between the lines.
Source: Wikipedia
Size
The adult’s wingspan is roughly 34 mm. The caterpillar can grow up to about 35 mm long.
Source: Wikipedia
Is it a pest in the house?
They are solitary defoliators that feed on foliage but do not cause serious damage to healthy trees.
Source: Wikipedia
Where it lives
It is common along the western coast of North America, from British Columbia down to California.
Source: Wikipedia
Life cycle
The caterpillar mimics twigs, overwinters as a mid-instar larva, pupates in June-July and emerges as an adult moth.
Source: Wikipedia
When you see it
Adults are seen from June through November, with numbers peaking in late summer.
Source: Wikipedia
Lookalikes
Similar species include Iridopsis pergracilis, Parapheromia cassinoi, Cymatophora approximaria (giant gray moth) and Pterospoda nigrescens.
Source: Wikipedia
Where it is found in the US
Recorded in 4 of 51 states and DC. Most records: California, Washington, Oregon, Alaska.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When are adult Brown-lined Loopers active?
Adults are on the wing from June to November, most common in late summer.
Source: Wikipedia
Same family (Geometridae)
Willow BeautyPeribatodes rhomboidaria
Pale BeautyCampaea perlataDamages trees, gardens or crops
Large Lace-border MothScopula limboundataDamages trees, gardens or crops
Riband WaveIdaea aversata
Yellow Shell MothCamptogramma bilineata
Large Maple Spanworm MothProchoerodes lineolaDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Neoalcis
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-23.