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How to identify it
- Look near the shoot tips for cocoon-like feeding shelters that incorporate frass, gnawed twigs and foliage, with browned or dying tips around them.[1][2]
- The full-grown caterpillar is about 10 mm long, reddish brown to blackish pink, with an unmarked brown head and two pairs of dark spots on the top of each abdominal segment.[1][2]
- The moth has a wingspread of about 20 mm and checkerboarded forewings. Adults emerge in July.[2][1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Cypress tip moth | The cypress tip moth or tipminer (Argyresthia cupressella) often occurs on the same trees. It belongs to a family of tiny mining moths; its white, paper-like cocoons among the leaflets of cypress, juniper and arborvitae give it away, whereas the cypress leaftier builds a shelter of frass, gnawed twigs and foliage.[2][1] |
| Juniper webworm | Juniper webworm caterpillars are light yellowish red with dark reddish-brown lines on the back and feed together in nests of webbed needles and frass on ornamental juniper. The cypress leaftier caterpillar is reddish brown to blackish pink with two pairs of dark spots per segment.[2][1] |
Where it lives
It is found from southern California north through Oregon and Washington into British Columbia, where it occurs throughout the south coastal region.[2][1]
Biology and life cycle
The principal hosts are western redcedar and various ornamental cedar, cypress and juniper species, including arborvitae, Chinese, common and Rocky Mountain junipers, eastern redcedar and yellow-cedar; grand fir is also listed. The USDA manual ranks ornamental cypress first, with arborvitae and juniper attacked to a lesser degree.[1][2]
The moth overwinters as a small caterpillar. Feeding resumes in March, when the caterpillar builds its shelter near a shoot tip from frass, gnawed twigs and foliage and feeds inside it.[1][2]
Pupation takes place in early June and the moths emerge in July.[1]
It often occurs together with the cypress tip moth, Argyresthia cupressella.[2]
Damage and signs
- The caterpillars tie and chew the foliage and twigs at the shoot tips. Natural Resources Canada says the insect occasionally causes visible shoot dieback on ornamental Cupressaceae, and the USDA manual says heavy infestations cause attacked trees to turn brown early in the spring.[1][2]
- The USDA manual rates it a significant pest of ornamental cypress, with arborvitae and juniper damaged to a lesser degree.[2]
Health risk
The sources treat it only as a pest of ornamental conifers and mention no effect on people.[1][2]
Control
Prevention
Because this moth often occurs together with the cypress tip moth, check for both when a cypress or cedar browns at the tips in spring; the leaftier is the one with an external shelter of frass and chewed twigs.[2][1]
Traps and physical control
From March on, look for the frass-bound shelters near the shoot tips of cypress, cedar and juniper and clip them off with the caterpillar inside; feeding continues until pupation in early June.[1]
Common questions
- What is making little clumps of frass and dead twigs on my cypress?
- Those are the feeding shelters of the cypress leaftier caterpillar, built near the shoot tips from frass, gnawed twigs and foliage from March until early June.[1]
- Why did my cypress turn brown in early spring?
- Heavy cypress leaftier infestations cause attacked trees to turn brown early in the spring, and Natural Resources Canada reports visible shoot dieback on ornamental cypress-family trees.[2][1]
- Which trees does it attack?
- Western redcedar and ornamental cedars, arborvitae, cypresses and junipers, with grand fir also listed. Ornamental cypress is the main victim, arborvitae and juniper less so.[1][2]
Sources
- Natural Resources Canada, Canadian Forest Service, “Cypress leaftier, Trees, insects and diseases of Canada's forests.” tidcf.nrcan.gc.ca/en/insects/factsheet/11025 (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, “Epinotia subviridis taxon page (order and family).” www.inaturalist.org/taxa/345436 (accessed 2026-11-10)