Pests

179 pests tracked across Western Washington landscapes, with identification, host plants, and management.

GDD Activity Timeline

Updated 2026-03-13

Pest emergence mapped to growing degree days (base 32°F). Puget Sound lowlands data with indicator plant correlations.

0 798 GDD₃₂ now 2,200

Already active

Winter moth 150 Pear psylla 584 White pine weevil 630 Bloodroot first bloom Tent caterpillar 672

Coming up

Root weevil NEXT 858 +60 to go Spruce spider mite 976 Serviceberry first bloom Boxwood psyllid 994 Serviceberry first bloom Codling moth 995 +197 to go Viburnum leaf beetle 1,085 Deutzia first bloom Azalea Lace Bug 1,099 Deutzia first bloom Birch leafminer 1,102 Deutzia first bloom Elm leafminer 1,116 Deutzia-Eastern redbud Boxwood leafminer 1,221 Crabapple first bloom Cooley spruce gall adelgid 1,424 Hawthorn first bloom Lilac borer 1,550 Hawthorn-Black locust Obliquebanded Leafroller 1,575 +777 to go Holly leafminer 1,625 Crabapple full bloom Elm leaf beetle 1,634 +836 to go Hemlock woolly adelgid 1,733 Red horsechestnut first bloom Oystershell scale 1,958 Tuliptree first bloom

GDD₃₂ estimates from UMD IPMnet, calibrated to Kent, WA accumulation curve. Indicator plants signal approximate pest activity timing.

Showing 179 pests

Acalitus essigi

Redberry mite

Affects 5 plants

Acanthococcus azaleae

Aculus schlechtendali

Apple rust mite

Affects 1 plant

Adelges cooleyi

Cooley spruce gall adelgid

Affects 20 plants

Adelges piceae

Balsam woolly adelgid

Affects 15 plants

Adelges tsugae

Hemlock woolly adelgid

Apple-and-thorn skeletonizer

Pear sawfly (pear slug)

Cherry slug (pear slug, cherry sawfly, pear sawfly)

Affects 1 plant

Chionaspis pinifoliae

Pine needle scale

Affects 78 plants

Choristoneura rosaceana

Obliquebanded Leafroller

Cinara occidentalis, Cinara abietis

Aphid

Affects 473 plants

Cinara occidentalis, Cinara abietis

Black cherry aphid

Affects 38 plants

Cinara occidentalis, Cinara abietis

Pear leafcurling midge

Cutworms and armyworms

Affects 70 plants

Cutworms and Armyworms

Cylindrocopturus furnissi

Dasineura gleditchiae

Honeylocust pod gall midge

Dialeurodes chittendeni

Rhododendron whitefly

Affects 132 plants

Diaspidiotus perniciosus

San Jose scale

Affects 56 plants

Dichomeris marginella

Juniper webworm

Affects 25 plants

Douglas-fir needle midge

Affects 4 plants

Douglas-fir twig weevil

Affects 4 plants

Drosophila suzukii

Spotted-wing drosophila

European Fruit Lecanium

Flat Headed And Shothole Borers

Brown marmorated stink bug

Insect contaminants at harvest

Leaf crumpler and Mineola moth

Lygus bug and plant bug

Nuculaspis californica

Lecanium scale

Affects 278 plants

Nuculaspis californica

Douglas-fir tussock moth

Affects 20 plants

Pacific flatheaded borer

Pear slug (Cherry slug)

Affects 38 plants

Pear Slug Pear Sawfly

Affects 0 plants

Phyllocoptes gracilis

Pearleaf blister mite

Pine Needle Sheathminer Pine Sheath Miner

Poplar and willow borer

Affects 15 plants

Poplar Petiole Gall Aphids

Affects 11 plants

Pseudococcus maritimus

Grape mealybug

Affects 1 plant

Pulvinaria floccifera

Cottony camellia scale

Affects 31 plants

Pulvinaria innumerabilis

Cottony maple scale

Affects 45 plants

Raspberry beetle (aka Western raspberry fruitworm)

Affects 0 plants

Raspberry Beetle Raspberry Fruitworm

Affects 4 plants

Raspberry crown borer

Affects 9 plants

Redhumped caterpillar

Affects 50 plants

Rhagoletis indifferens

Western cherry fruit fly

European pine shoot moth

Spiny elm caterpillar

Stephanitis pyrioides

Azalea Lace Bug

Affects 135 plants

Stephanitis rhododendri

Rhododendron lace bug

Affects 132 plants

Stigmaeopsis celarius

Strawberry crown moth

Twospotted spider mite

Maple Bladdergall Mite

Western flower thrips

Affects 46 plants

Western tentiform leafminer

Affects 1 plant

Xanthogaleruca luteola