Euonymus Scale

Euonymus scale, Unaspis euonymi, is an armored scale that is a very common pest of euonymus and pachysandra. Although the individual insects are small, infestations are often dense and plainly visible.

Euonymus scale is now established in the United States and Canada and has become a major concern in many landscapes. Without treatment, heavy scale infestations will reduce photosynthesis, stunt plants, cause leaves to fall off, and kill all or part of the plants.

Treatment Strategy

Management of euonymus scale with contact insecticides may be difficult because of the waxy covering that protects the insects most of their lives. Newly hatched crawlers are the easiest to control with contact insecticides. Monitoring for scale crawler emergence is important to create an effective management program. Examine individual trees by tapping a branch over a white sheet of paper and looking for crawlers during the period when crawlers are expected.

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Euonymus Scale Treatment Option 1

Multiple applications of a contact insecticide like Up-Star® Gold are recommended because egg hatch occurs over several weeks.

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Euonymus Scale Treatment Option 2

Transtect, a soil-applied systemic insecticide, is effective for season long control of euonymous scale if applied in the spring.  Moving through the plant where the insect feeds, Transtect eliminates the need for multiple sprays and constant monitoring, making treatment more manageable.

Application Type Soil drench

DIY Product/Equipment Needed:

• Transtect

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Euonymus Scale DIY Kit

Option 1

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Option 2

Application Type Soil drench

DIY Product/Equipment Needed:

• Transtect

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

How Is It Spread?

Eggs are laid in early spring and hatch in late May or early June.  The young nymphs crawl to other parts of the host plant before settling down to begin feeding.  Once settled, they secrete their waxy protective covering and produce a second generation by mid-July, and a third generation in October.

Susceptible Trees

Wintercreeper, American bittersweet, English ivy, Japanese pachysandra, boxwood, privet, honeysuckle, canby paxistima, holly, stone fruits, and daphne.

Symptoms

  • Yellowish stippling or spotting of the foliage.
  • Heavy infestations may occur on twigs or leaves that can cause defoliation of the plant.
  • Twig dieback or death of the plant.
  • Females are dark brown or gray, about 1/16” long and pear-shaped; they are commonly found on the stems of host plants.
  • Males are 1/32 in. long, narrow, white with a yellow cap at one end, and often more abundant than females.
  • Eggs and crawlers are tiny and yellow.

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