Managing Euonymus Scale Infestation in Pachysandra Beds

Pachysandra beds are susceptible to infestations that may manifest as odd-looking white spots. If you notice these on your plants, it could indicate a euonymus scale infestation. This pest is known for its piercing-sucking mouthparts that feed on plant sap, leading to potential damage.

Euonymus scale adults create protective coverings over themselves, making control challenging, as most insecticides are ineffective against armored scales. However, it’s crucial to address the issue when populations grow large. Initially, you may not need to take any immediate action.

Female euonymus scales overwinter on plants and begin egg-laying from late April through May. Eggs hatch into crawlers over two to three weeks. Male scales feed under narrow, white, waxy coatings, mating with females in spring. The crawlers subsequently wander for a short period before feeding and forming their waxy coverings. A second crawler generation occurs from late July through August.

The optimal time for controlling these pests is during the crawler stage. Consider pruning out infested pachysandra areas by next March to eliminate overwintering females. Ensure plant debris is discarded in the garbage or sent to a commercial landscape waste facility, where compost piles reach temperatures high enough to kill the pests.

“Applying control measures during the crawler stages in late May to early June and late July to August is effective.”

Reduce pest populations significantly by removing overwintering adults from your garden. Utilize summer-weight dormant oil on pachysandra during the crawler activity for enhanced pest control.

If you require further plant advice, contact the Plant Information Service at the Chicago Botanic Garden via [email protected]. Tim Johnson serves as the senior director of horticulture at the Chicago Botanic Garden.