Scale insects are common and often frustrating-to-manage insect pests of ornamental trees and shrubs. There are also many different kinds (Families) of scales, in addition to a large number of species of scale insect pests of important host plants in our landscapes. The main Families of scale insects discussed in this guide, and corresponding species are combined and sorted by Family here:
Asterolecaniidae (Pit Scales)
- Asterodiaspis variolosa - golden oak scale
Coccidae (Soft Scales)
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Eulecanium spp., Parthenolecanium spp. and others - lecanium scales
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Neolecanium cornuparvum - magnolia scale
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Neopulvinaria innumerabilis (formerly Pulvinaria innumerabilis) or Pulvinaria acericola - cottony maple scales
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Parthenolecanium fletcheri - Fletcher scale
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Parthenolecanium quercifex - oak lecanium scale
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Physokermes hemicryphus - spruce bud scale
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Pulvinaria floccifera - cottony camellia scale/cottony taxus scale
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Toumeyella liriodendri - tuliptree scale
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Toumeyella parvicornis - pine tortoise scale
Diaspididae (Armored Scales)
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Aspidiotus cryptomeriae - cryptomeria scale
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Carulaspis juniperi - juniper scale
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Carulaspis minima - minute cypress scale
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Chionaspis pinifoliae - pine needle scale
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Comstockaspis perniciosa - San José scale
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Dynaspidiotus californicus - black pineleaf scale
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Dynaspidiotus tsugae - shortneedle evergreen scale
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Fiorinia externa - elongate hemlock scale
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Hemiberlesia ithacae - hemlock scale
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Lepidosaphes pallida - Maskell scale
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Lepidosaphes ulmi - oystershell scale
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Lepidosaphes yanagicola - scale on Euonymus alatus (fire bush scale)
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Melanaspis obscura - obscure scale
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Melanaspis tenebricosa - gloomy scale
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Pseudaulacaspis pentagona - white peach scale
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Pseudaulacaspis prunicola - white prunicola scale
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Unaspis euonymi - euonymus scale
Eriococcidae (Felt Scales)
- Acanthococcus azaleae - azalea bark scale
- Cryptococcus fagisuga - beech scale
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Gossyparia spuria - European elm scale
Kermesidae (Gall-like Scale Insects)
- Allokermes spp. - Kermes oak scale
Matsucoccidae (Formerly Margarodidae)
- Matsucoccus gallicolus - pine twig gall scale
See individual entries for each species within this Guide for further details and specifics.
Damage to the host plant depends upon the species of scale insect and possibly also the host plant involved. Scales, in general, can cause discoloration of the foliage, needle or leaf loss, chlorosis, dieback, pit formation, and even host plant mortality. See each individual species entry for further details. Some scale insects also make it easier for certain species of fungi to invade their host plants, thus leading to disease. The host list above is abridged to hosts of the soft scales (Coccidae) included in this Guide, only.
See each individual species entry for further information. Monitoring times (during the season) vary depending upon scale species. Crawlers may be active at different times of year, or overlapping generations may be present. Additionally, symptoms of scale infestation may be slightly different depending upon the species of scale or host plant involved. See each individual species entry for further details.
Trees under drought stress in managed landscapes or urban forests may have more trouble with scale infestations than those without stress. Practices such as adequate watering during these times may help support tree health and reduce additional stressors. Prune and remove and destroy heavily infested branches if possible without compromising tree shape or health. Some soft scales are large enough to remove from host plants (when practical) with a soft brush. See each individual species entry for further details.
Parasitoid wasps, lady beetle and other insect predators, pathogens, and certain abiotic conditions as well as competition can influence scale populations. See each individual species entry for further details.
Abamectin (NL)
Acephate (NL)
Acetamprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Chlorpyrifos (N)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Dinotefuran (NL)
Flonicamid+cyclaniliprole (N) (soft scales)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (L)
Neem oil (NL)
Pyrethrin + sulfur (NL)
Pyriproxyfen (L)
Spinetoram + sulfoxaflor (N)
See individual scale species for information regarding specific host plants.
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamprid (injection), azadirachtin (injection, soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), imidacloprid (soil drench), and neem oil (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
