On this page
How to identify it
- The full-grown caterpillar is up to 25 mm long and bright green, with a thin dark green stripe down the middle of the back, a white stripe on each side of the back that runs onto the head, and a white stripe along the spiracles. The head is brown with a cream herringbone pattern on each lobe and a green frontal triangle.[1]
- The USDA manual describes the larva as green with two conspicuous near-white stripes down the back.[2]
- The moth resembles that of the variable girdle moth: a wingspan of 37 to 39 mm and pale gray brown wings with fine darker bands.[2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Variable girdle moth | The variable girdle moth (Sabulodes venata) shares the hosts and has a similar adult, but its caterpillar is rusty or pale golden brown with broken blackish lines, not bright green with white stripes.[2][1] |
| Enypia griseata | Natural Resources Canada says Enypia griseata is very similar and is told apart by its different distribution.[1] |
Where it lives
It is generally distributed throughout coastal British Columbia and ranges north to southern Alaska and south to California; the USDA manual calls it a coastal form occurring from southern Alaska to southern California.[1][2]
Biology and life cycle
The principal hosts are Douglas-fir and western hemlock; amabilis fir, grand fir, western redcedar, Sitka spruce and mountain hemlock are also fed on. The caterpillars feed singly on the current year's foliage and move about freely on it.[1][2]
The species overwinters as a fourth- or fifth-instar caterpillar, which resumes feeding in spring and finishes in May or June. The pupal stage lasts about 21 days between June and July, and the moths fly from June to August. Females lay about 55 eggs on foliage; the caterpillars hatch about two weeks later and feed until cold weather sets in.[1]
Damage and signs
Health risk
The sources describe it only as a conifer needle feeder and mention no effect on people.[1][2]
Control
Prevention
No control is needed; the caterpillars feed singly and the sources record no significant damage to the host trees.[1][2]
Common questions
- What is the green inchworm with white stripes on my Douglas-fir?
- On the Pacific coast from Alaska to California, a bright green caterpillar up to 25 mm long with white stripes along the back and sides, a thin dark green midline and a brown herringbone-patterned head on Douglas-fir or western hemlock is Packard's girdle moth.[1]
- Is it the same as the redheaded looper?
- Yes. The USDA Forest Service manual calls Enypia packardata the redheaded looper; iNaturalist lists the species as Sabulodes packardata, Packard's girdle.[2][3]
- Does it need treatment?
- No. It is common but innocuous, and no significant damage is recorded.[1][2]
Sources
- Natural Resources Canada, Canadian Forest Service, “Packard's gridle [girdle] moth, Enypia packardata, Trees, insects and diseases of Canada's forests.” tidcf.nrcan.gc.ca/en/insects/factsheet/8595 (accessed 2026-11-10)
- USDA Forest Service, “Western Forest Insects, Miscellaneous Publication 1339 (R. L. Furniss and V. M. Carolin, November 1977; scanned copy).” archive.org/details/CAT78702369 (accessed 2026-11-10)
- iNaturalist, “Sabulodes packardata taxon page (order and family).” www.inaturalist.org/taxa/1378554 (accessed 2026-11-10)