Melanaspis tenebricosa

Gloomy scales. Photo: John A. Davidson, Univ. Md, Bugwood.
Scientific Name: 
Melanaspis tenebricosa
Common Name: 
Gloomy Scale
Growing Degree Days (GDD's): 
Not available at this time.
Host Plant(s) Common Name (Scientific Name): 
Boxelder (Acer negundo)
Buckthorn (Rhamnus spp.)
Catalpa (Catalpa spp.)
Dogwood (Cornus spp.)
Elm (Ulmus spp.)
Hackberry (Celtis spp.)
Inkberry (Ilex glabra)
Mulberry (Morus spp.)
Red maple (Acer rubrum) *Preferred host.
Silver maple (Acer saccharinum) *Preferred host.
Sugar maple (Acer saccharum)
Sweetgum (Liquidambar spp.)
Sycamore (Platanus spp.)
Tupelo (Nyssa spp.)
Insect Description: 

Adult female gloomy scales appear covered with a convex, circular, and brown to gray armored coating (test) and are approximately 1/8 of an inch in diameter. Adult males have similar covers, but may be elongate. Both are black when rubbed. The body of the adult female, hidden beneath this covering, is pink or purple. Eggs of this insect are faint pink in color and the crawlers (mobile immature stage) are cream colored. This armored scale insect is found on the bark of its host plants. One generation per year has been reported in Maryland. Fertilized females reportedly overwinter. Egg laying is observed in early July and continues through August. Eggs hatch almost immediately, and pale straw-yellow crawlers are also present during this time frame. Winged adult males are reported from mid-August to mid-September. This is a native scale insect that has been reported from much of the eastern US. In the field, this scale may be confused for the obscure scale (Melanaspis obscura) which is similar in appearance, with the exception that obscure scales favor oaks (Quercus spp.).

Damage to Host: 

Red and silver maples may be the most impacted. Reports of the activity of this insect range from a significant pest that may lead to tree mortality to an occasional pest. This insect occurs primarily in the eastern US, and has been reported as far north as New York. Scales typically settle on 1 to 4 year old branches. Heavy infestations cause stunting and dieback. Some report that street trees are more significantly impacted by this insect.

Monitoring: 

While this insect has been reported only as far north as NY, it is likely that it is easy to transport gloomy scales (like many other scale insects) on infested nursery stock. Johnson and Lyon (1991) report that trees in nurseries as well as landscaped settings are frequently injured by this insect, but that it is a primary pest of silver and red maples. Miller and Davidson (1990) consider this insect to only be an occasional pest. Look for gloomy scales on the bark of branches. Convex, gray scale covers of the immatures may be seen in the winter. Adult female scale covers may be noticeable in the summer months.

Cultural Management: 

If practical and the scales are limited to individual branches, prune and remove them to help reduce the scale population.

Natural Enemies & Biological Control: 

The gloomy scale has been reported as a host for the parasitoid wasps, Encarsia citrina as well as Thysanus nigrellus. A fungus also reportedly impacts these scales, Cosmospora flammea.

Chemical Management: 

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 (L)

Spinetoram + sulfoxaflor (N)

Notes: 

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.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: September 27, 2024. To check current product registrations in Massachusetts, please visit the MA Department of Agricultural Resources Pesticide Product Registration page and click on "Search Pesticide Products Registered in Massachusetts - Kelly Solutions".