White Insects on Euonymus

Identification

• One of the most common euonymus pests is euonymus scale (Unaspis euonymi). Only the male has a white protective armor covering. Aphids can be many colors and some secrete a waxy white substance that covers their bodies. These tiny, slow moving insects tend to cluster together and prefer tender, new growth.

Damage

• Both scale insects and aphids feed on euonymus by sucking the juices from the plant. Scales typically hide on the undersides of leaves, so look for yellow spots on the leaves as an indication the plant is infested. If not dealt with, the infestation will grow and the pests may kill the plant. A small aphid infestation won’t damage the euonymus. Large populations cause yellowing of the leaves and stunted growth. Aphids also secrete honeydew, a sticky substance that attracts sooty mold. Finally, some aphids transmit diseases that may cause curled, yellow foliage.

Prevention

• Planting pest-resistant cultivars, such as winged euonymus "Compactus" (Euonymus alatus “Compactus”) or wintercreeper “Acutus” (Euonymus fortune “Acutus”), is the best way to prevent scale infestations. If you’re growing one that isn’t resistant, spray it in spring, just before it produces new growth, with a ready-to-use horticultural oil spray. To prevent the eggs from hatching they must be covered with the spray so ensure that the entire plant is covered to the point of runoff. Avoid over-fertilizing the euonymus. Too much nitrogen causes rapid growth of tender new shoots which attract aphids.

Control

• Because of their waxy, protective covering, euonymus scale is quite challenging to control. Deal with small infestations by scraping the insects off the plant by hand. Large infestations may require pruning the euonymus to remove the infested parts. Control aphids by spraying the plant with a blast of water from the hose.