Lepidosaphes pallida, or the Maskell scale has been reported from at least 21 genera of plants in 15 plant families, including Cryptomeria spp., Sciadopitys spp., and Pinus thunbergiana (ScaleNet). Maskell scales, when present
on Cryptomeria, can cause browning and twig dieback. On other hosts (such as juniper and certain cedars) this species has been reported to be a serious pest in the literature. To our knowledge, the Maskell scale has not yet officially been reported (in the literature) in Massachusetts, although it is found in New Jersey, New York, Delaware, Pennsylvania, and at least seven additional US states and is likely more widespread than what is currently known.
Adult scales are 1/16th of an inch in length, brown, and oystershell-shaped. Specifically, the adult female scale is oyster-shell shaped, light brown, and sometimes white in color near the rear end. The body of the adult female is white in color, if the test (armored covering) is removed. Male scales are shorter, more narrow, and light brown. The crawlers (immatures) are pale-yellow to white and have been reported in other states to be active in June and August. Crawlers have been targeted for management in New Jersey in June and again in August. Cornell Cooperative Extension recommends checking for crawlers in early June. Unfortunately, not much is known about the biology and life cycle timing of this insect. What has been recorded about the biology of this insect is from New Jersey and is as follows: mated females overwinter, and on Japanese black pine hosts, females have been found to lay 3-6 white colored eggs each in May; crawlers emerge by the last half of June and first instar crawlers settle on new growth. In NJ, a partial second generation has also been recorded (Kosztarab, 1996).
The damage caused by this armored scale insect varies. On Cryptomeria, browning of the foliage and possible twig dieback may occur. Heavily infested host plants may turn yellow, and certain species may be killed without intervention. This insect may be a serious pest of its hosts in certain locations or if other plant stressors are co-occurring.
Scout for the presence of the adults or immature stages of the Maskell scale on the needles of potential hosts. The armored tests (coverings) of the adult males and females may cling to the needles, even following the death of the insect. Crawlers may be present in June or August. Check trees and shrubs with symptoms of yellowing or browning of the needles or sparse foliage. Because this is an armored scale, no honeydew is produced (and therefore no sooty mold will be visible either).
Prune out and destroy discolored or heavily infested branches. As always, reducing additional stress and planting host plants on the correct site will help reduce the impact of the feeding of insect pests.
A single natural enemy of the Maskell scale is noted from the family of parasitoid wasps known as the Aphelinidae. The species Aphytis hispanicus is a tiny, non-stinging wasp that is noted as a parasitoid of this armored scale (Rosen and DeBach, 1979).
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Chlorpyrifos (N) (labeled for use against scales)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL) (crawlers)
Dinotefuran (NL)
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)
Dormant oil applications may be made when spring temperatures allow for safe application. If the population is heavy and damage is severe, a summer oil, contact insecticide, or systemic insecticide may be necessary in June; if crawlers are again seen in August, repeat applications in August may be necessary. Cornell Cooperative Extension notes that crawlers may be active in early June and that repeat applications of contact insecticides (foliar applications) may be needed every 7-10 days for a total of 2-3 times for heavy infestations, if allowable when following label instructions for the product.
When used in a nursery setting, chlorpyrifos is for quarantine use only.
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (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.
