How to identify it
- Mature females are dome-shaped (almost hemispherical) soft scales, light brown to yellowish or dark brown, sitting on twigs and stems.[1][2]
- Crawlers are tiny, flat, oval and yellowish to yellow-orange; overwintering nymphs are small and brownish on twigs and needles.[1][2]
- Honeydew and sooty mold on twigs and foliage in spring are often the first sign.[1][2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| European fruit lecanium | It looks very similar but attacks a much broader range of plants; on yew and arborvitae, Fletcher scale is the likelier one.[2] |
Where it lives
It is native to the United States and attacks arborvitae, yew and juniper, with cypress and other conifers reported as hosts.[1][2]
Biology and life cycle
It has one generation a year and overwinters as second-stage nymphs on twigs and needles.[1][2]
The nymphs mature in spring, and females lay eggs beneath their bodies by late May to early June; females can reproduce without mating.[1][2]
Crawlers hatch from June into July and settle nearby on needles, bud scales or branches.[1][2]
Damage and signs
Health risk
It feeds on plants; Utah State and UMass Extension mention no risk to people.[1][2]
Control
Prevention
In spring, look for honeydew and sooty mold and check twig tips for swollen females; search several branches when numbers are low.[2]
Sanitation
Because crawlers don't move far, heavily infested branches can be pruned out and destroyed before eggs hatch in June.[2]
Biological control
Parasitic wasps, lacewings and other natural enemies attack it, so choose reduced-risk options when treatment is needed.[2]
Pesticides
Sprays such as horticultural oil or insecticidal soap should be timed to crawler activity; Utah State also lists a systemic insecticide in spring after leaves expand.[1]
Common questions
- What are the brown bumps on my yew twigs?
- Dome-shaped brown bumps with sticky honeydew and sooty mold nearby are often Fletcher scale.[1][2]
- When should I treat Fletcher scale?
- Time treatments to the crawlers, which hatch from June into July.[1][2]
- Can I just prune it out?
- Yes, if it is limited to a few branches: prune and destroy them before the eggs hatch in June.[2]
Sources
- Utah State University Extension, “Fletcher Scale (Ornamental Pest Guide).” extension.usu.edu/planthealth/ipm/ornamental-pest-guide/arthopods/scales/fletcher-scale (accessed 2026-10-06)
- UMass Extension Landscape, Nursery and Urban Forestry Program, “Parthenolecanium fletcheri (soft scale).” www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/parthenolecanium-fletcheri-soft-scale (accessed 2026-10-06)
- iNaturalist, “Parthenolecanium fletcheri taxon page (order and family).” www.inaturalist.org/taxa/1006646 (accessed 2026-10-06)