This scale is found on the underside of host plant needles. It looks like a "fried egg" and mature females are approximately 1/20 of an inch in length. Mature males have wings and are rarely observed. Two generations per year have been reported in Maryland. Second instar nymphs (immatures) have been reported as overwintering. Adults may be observed in March and April. Eggs are reportedly laid by females in June which develop into second generation adults by mid-July. (Eggs are yellow in color and oval in shape.) A second generation of eggs is laid in late August and September. Crawlers appear in June and August, and their emergence may last several weeks. Crawler emergence is thought to peak approximately 2-3 weeks after eggs are laid. Each generation is not synchronous, meaning not all individuals mature at the same time and so multiple life stages may be present.
Yellowing or yellow spotting may be seen on host plant needle surfaces, particularly on hemlock. Pines and firs may develop blotchy, yellow-brown coloration. In addition to discoloration, branch dieback may occur with heavy infestations. This insect can be a major pest in Christmas tree plantations.
Look for discolored needles on susceptible host plants. Check the undersides of needles for the hardened scale covers and/or yellow crawlers. Crawlers present in June and August. Scout for scale insects on the underside of needles on the inside of bottom branches first. Scouting on overcast days may make it easier to see the symptoms caused by cryptomeria scale infestation. Yellow sticky cards can be placed in infested trees to aid in scouting for adult (winged) male emergence. Egg laying will begin soon after males are seen. Check scale covers for round exit holes left behind by natural enemies.
If infestations are restricted to a single branch or small area that may be pruned out without otherwise impacting the overall health of the host or its aesthetic value, the removed material may be discarded/destroyed. In Christmas tree production, if the scales are found on only a few trees, consider cutting and destroying those trees to prevent the scales from spreading further.
Hymenopteran parasites have been observed. Look at the armored scale tests (coverings) for round exit holes indicating parasite activity. If the activity seems common, use only insecticidal soap or horticultural oil applications to manage this scale in ornamental landscapes. Encarsia citrina, Chilocorus renipustulatus, Comperiella bifasciata, and Comperiella indica have all been reported to attack cryptomeria scales (Murakami, 1970 and Japoshvili et al, 2013).
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Buprofezin (NL)
Carbaryl (L)
Chlorpyrifos (N)
Clothianidin (NL)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Dinotefuran (NL)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (L)
Neem oil (NL)
Pyrethrin+sulfur (NL)
Pyriproxyfen (eggs) (L)
Spinetoram+sulfoxaflor (N)
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.
