Armored Scale - Trees and Shrubs

• Mature female covers are rounded, brown to gray over black, and up to ⅛” (3mm) in diameter. Individuals may be overlapping.
• Male covers are oval, similar in color, and smaller.
• Crawlers are pink.

• Various oaks, particularly black oak (Quercus velutina), pin oak (Quercus palustris), and willow oak (Quercus phellos)
• Pecan (Carya illinoinensis)

• All life stages will be found on the bark, especially on three- to four-year-old branches.
• Gnarled or disfigured branches (or trunks on young trees) can occur from dense and overlapping clusters of live scale damaging the bark.
• Overfertilized trees are more vulnerable to heavy outbreaks. This includes sites where trees are surrounded by lawn receiving excessive nutrients.

• Heavy or prolonged infestations can cause premature leaf drop and branch dieback, plus a rougher, sunken appearance to the bark under dense scale clusters.

• There is 1 generation per year in Maryland.
• The crawler emergence period depends on temperature and can vary slightly from year to year. The approximate time to monitor for them is July through mid-September.
• They overwinter on the bark as juveniles.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

1774 degree days

After the peak flowering of Golden Raintree (Koelreuteria paniculata)

During the peak flowering of Rose-of-Sharon (Hibiscus syriacus)

Natural enemies are active during the beginning of the crawler period. Conserve them by avoiding the use of long-residual pesticides during this time.

Contact insecticides may have limited efficacy since crawlers often shelter under the covers of dead scale from prior generations.

• Mature female covers are oystershell-shaped, brown to gray, sometimes with yellow bands, and up to ⅛” (3mm) in length.
• Male covers are similar but smaller.
• Crawlers are pale yellow.

Over thirty plant families are used by this species.

• Preferred shrubs include lilac (Syringa), boxwood (Buxus), and cotoneaster (Cotoneaster).
• Preferred trees include beech (Fagus), birch (Betula), ash (Fraxinus), maple (Acer), poplar (Populus), willow (Salix), elm (Ulmus), flowering cherry (Prunus), dogwood (Cornus), and fruit trees.

• All life stages will be found on the bark.

• High populations can cause leaf yellowing and wilting, followed by branch dieback. Prolonged infestations can kill small plants.

• There are 1 or 2 generations per year in Maryland (depending on population genetics).
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – April
  • Second generation – early May through June
• They overwinter as eggs sheltered under female covers.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

• First generation – no local data available
• Second generation – 486 degree days
  
  During the first flowering of thornless honeylocust (Gleditsia triacanthos f. inermis), Japanese snowbell (Styrax japonicus), and tulip poplar (Liriodendron tulipifera)

• Mature female covers are rounded, white with yellow center, and up to 1/16” (1.5mm) in diameter.
• Male covers are elongate, white, and 1/16” (1.5mm) in length.
• Crawlers are white or salmon/coral pink.

Over 250 plant genera in 89 families are used by this species.

• shrubs red-twig dogwood (Cornus alba) and beautyberry (Callicarpa)
• preferred trees include peach (Prunus persica) and other stone fruits plus flowering cherry (Prunus), white mulberry (Morus alba), black willow (Salix nigra), and persimmon (Diospyros)

• All life stages will be found on the bark.
• Juvenile males tend to congregate on the underside of branches in snowy-looking clusters.
• Infestations tend to begin on outer or smaller branches associated with leaf yellowing and dieback.

• High populations cause leaf yellowing and premature shedding, followed by stunting and branch dieback. Prolonged infestations can kill small plants.

• There are 3 generations per year in Maryland.
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – mid-May through mid-June
  • Second generation – mid-July through mid-August
  • Third generation – September
• They overwinter as adult females.

No local Growing Degree Days and Plant Phenological Indicator data have been compiled for this species.

• Mature female covers are oystershell-shaped, white with yellow tip, and up to ⅛” (3mm) in length.
• Male covers are similarly shaped, white, and smaller (2mm).
• Crawlers are reddish.

• Prefers pines, such as eastern white pine (Pinus strobus), mugo pine (Pinus mugo), Scotch pine (Pinus sylvestris), and Austrian pine (Pinus nigra).
• A variety of needled conifers are also used, including spruce (Picea), fir (Abies), hemlock (Tsuga), and cedar (Cedrus).

• All life stages will be found on foliage (needles).
• Trees under stress. Trees growing against buildings and along roads are more prone to damaging infestations of this scale due to the stress caused by pollution, limited root space, and reflected heat.

• Light infestations cause little damage.
• Heavy or prolonged infestations can cause premature needle yellowing, stunted growth, and dieback.

• There are 2 generations per year in Maryland.
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – May
  • Second generation – early July through late August
• They overwinter as eggs sheltered under female covers.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

• First generation – 307 degree days
  
  During the flowering of mayapple (Podophyllum peltatum) and flowering dogwood (Cornus florida)
  Before the peak flowering of red buckeye (Aesculus pavia)
   

  

  

  

• Second generation – 1561 degree days
  
  Before the peak flowering of golden raintree (Koelreuteria paniculata)
  After the first flowering of swamp milkweed (Asclepias incarnata) and rose-of-sharon (Hibiscus syriacus)
   

  

  

  

  
   

• Mature female covers are oval or elongate, translucent aging to tan, and 3/16” (4.75mm) in length.
• Male covers are similar but smaller.
• Crawlers are yellow.

Utilizes thirteen genera in four families, all conifers.

• Prefers pine (Pinus), hemlock (Tsuga), and fir (Abies)
• Yew (Taxus), falsecypress (Chamaecyparis), juniper (Juniperus), and plum yew (Cephalotaxus) may be used. Despite the scale’s name, Cryptomeria (Cryptomeria) is a rarer host in the U.S.

• All life stages will be found on foliage (needles).

• Light to moderate infestations cause needle discoloration, with hemlock developing yellow blotches and pine and fir developing yellow to brown blotches.
• Heavy or prolonged infestations can cause dieback.

• There are 2 generations per year in Maryland.
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – mid-June to early July
  • Second generation – late August through September
• They overwinter as juveniles.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

• First generation – 937 degree days
  
  After the first flowering of Japanese stewartia (Stewartia pseudocamellia)
  Before the peak flowering of witherod viburnum (Viburnum nudum)
   
• Second generation – no local data available
   

  

  

• Mature female covers are elongate, translucent tan over reddish-brown, and 3/16” (4.75mm) in length.
• Male covers are elongate, white with waxy threads, and smaller.
• Crawlers are lemon-yellow.

See the cryptomeria scale illustration for comparison with this species.

• Prefers hemlock (Tsuga)
• Spruce (Picea), fir (Abies), and yew (Taxus) are also used

• All life stages will be found on foliage (needles).
• Needle discoloration can resemble spider mite damage. Dense scale populations can give needles a whitewashed appearance.

• Light to moderate infestations cause yellow spotting on needles.
• Heavy infestations cause premature needle drop and eventual tree death (even for mature plants).

• There are 2 overlapping generations per year in Maryland.
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – May
  • Second generation – mid-June through early October
• They overwinter as adult females or as eggs sheltered under female covers.

No local Growing Degree Days and Plant Phenological Indicator data has been compiled for this species.

• Mature female covers are oystershell-shaped, light brown, and up to 1/16” (1.5mm) in length.
• Male covers are similar but smaller.
• Crawlers are pale yellow.

Twenty-one genera in fifteen plant families – both conifer and broadleaf – are used by this species.

• Prefers cryptomeria (Cryptomeria japonica), Japanese umbrella-pine (Sciadopitys verticillata), and Japanese black pine (Pinus thunbergii)

• All life stages will be found on foliage (needles). Due to their very small size and tendency to tuck into the sheaths between needles (on pine) or around needle bases, they will be difficult to see. Only high populations produce more detectable signs of scale on the surface of damaged needles.

• Light infestations may cause little damage but also tend to go undetected without close inspection.
• Heavy infestations cause needle browning and branch dieback on cryptomeria. Needles on pine and umbrella-pine yellow before browning. Young foliage may be stunted.

• There are 2 generations per year in Maryland.
• The crawler emergence periods depend on temperature and can vary slightly from year to year. The approximate times to monitor for them are:
  • First generation – June
  • Second generation – August
• They overwinter as mated adult females.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

• First generation – 470 degree days
  
  During the first flowering of thornless honeylocust (Gleditsia triacanthos f. inermis) and Japanese snowbell (Styrax japonicus)
  During the flowering of false indigo (Baptisia)
   

  

  

  

• Second generation – 2035 degree days
  
  Before the first flowering of Japanese pagodatree (Styphnolobium japonicum) and Natchez crapemyrtle (Lagerstroemia ‘Natchez’)
   

  

  

• Mature female covers are circular, white with a yellow patch, and up to ⅛” (3mm) in diameter.
• Male covers are elongate, white, and smaller.
• Crawlers are tan.

Fifteen genera in four conifer families are used by this species.

• Prefers juniper (Juniperus), spruce (Picea), and leyland cypress (Cupressocyparis leylandii)

• All life stages will be found on foliage (needles).
• Cultivars that grow densely and narrowly upright (columnar forms) may be more susceptible to outbreaks of this scale.

• Heavy infestations can cause needle yellowing followed by browning, and later branch dieback.

• There is 1 generation per year in Maryland.
• The crawler emergence period depends on temperature and can vary slightly from year to year. The approximate time to monitor for them is May to early June.
• They overwinter as adult females.

Just before the expected emergence period, start monitoring for crawlers. Since weather trends can shift date ranges, a more reliable prediction of timing can be made using Growing Degree Days and Plant Phenological Indicators. A refined estimate of egg hatch and the beginning of crawler emergence is:

• 511 degree days
  
  During the peak flowering of tulip poplar (Liriodendron tulipifera), green hawthorn (Crataegus viridis ‘Winter King’), and Virginia spiderwort (Tradescantia virginiana)