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Euonymus Scale

| By | Pests

Euonymus Scale (Unaspis euonymi)

GDD Window (base 50): 533-820

Overview:​

  • Armored scale, waxy covering protects them from predators and pesticides (Overwinter on bark as mated females)​
  • Scale crawlers are light-yellow in color and active during early June when Kousa dogwood is in bloom            ​
  • Males are white, thin, and elongated, feeding on leaves causing yellow spots (Male adults fly & die after 24 hours ​
  • Females are dark-brown, oyster-shell shaped, and larger than the males, feeding on branches ​
  • 2 overlapping generations per year (early June and August)​
  • High populations result in defoliation and a decline in plant health ​
  • Crawlers have 1-2 days after hatching before they must settle & start feeding (Feed within plant cells)
  • Host plants: Variegated evergreen euonymus, Japanese pachysandra, boxwood, bittersweet, & Allegheny spurge 

Management:

Cultural Practices:
  • Natural predators:  brown lacewings, green lacewings, lady beetles, &  Parasitoid wasps ​
  • Prevent dusty conditions​
  • Reduce plant stress​
  • Dispose of heavily infested plants 
Materials:
  • Contact insecticides:​
    • Carbamates [1A]: carbaryl​
    • Pyrethroids [3A]: –thrins​
    • Organophosphates [1B]: acephate (translaminar), malathion​
  • Considerations:​
    • Will harm non-target species​
    • Timing is essential in controlling armored scales (target crawler stage before waxy covering forms)​
  • Systemic insecticides:​
    • Neonicotinoids [4A]: dinotefuran, acetamiprid, thiamethoxam​
    • Tetronic acids [23}: spirotetramat 
Biorationals:
  • Insecticidal soaps and Horticultural oils​
    • Neem oil​
  • Insect growth regulators:​
    • Pyriproxyfen [7A]​
    • Buprofezin [16]
Yellow colored Euonymus Scale crawlers emerging. These crawlers moved to leaves from branch stems where the female mostly feed. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Euonymus Scales have sexual dimorphism with females being dark gray & oyster-shell shaped while males are white & narrowly elongated. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Turn over on the undersides of the Pachysandra leaf & signs from mostly males & a few females are found feeding. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Disclaimer – Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible form is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss treatments with your local agents. Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed applicators. Guidelines and recommendations made in this presentation are specific to the state of New Jersey.