Cottony Cushion Scale: Effective Two-Step Treatment Plan

Controlling Heavy Cottony Cushion Scale Infestations

Those thousands of white, cottony masses covering stems and leaf undersides are cottony cushion scale (Icerya purchasi)—a sap-sucking insect that can severely weaken shrubs if untreated.

Identification

Adult females produce distinctive white, fluted egg sacs (ovisacs) that resemble cotton. Crawlers (mobile nymphs) spread to new growth. Heavy infestations cause yellowing, leaf drop, and dieback.

Two-Step Treatment Protocol

Step 1: Horticultural Oil (Immediate)

• Spray thoroughly under all leaves and around stems
• Suffocates adults and many crawlers
• Apply when temperatures are 45-85°F
• Ensure complete coverage—this is critical

Step 2: Acetamiprid (Two Weeks Later)

• Use Ortho Fruit, Flower & Vegetable Spray or similar product
• Follow label directions exactly
• Targets surviving crawlers and newly hatched nymphs
• Systemic action protects new growth

Expected Timeline

Insects should begin turning brown within a month. Monitor for reinfestation and retreat if necessary. Ants often "farm" scale for honeydew—controlling ants can reduce spread.

Prevention

• Inspect new plants before purchase
• Encourage natural enemies (lady beetles, parasitic wasps)
• Avoid excessive nitrogen fertilization
• Prune for good air circulation

Heavy cottony cushion scale on stems and leaf undersides

Close view showing fluted egg sacs

Scale insects on leaf underside

Detail of adult females with egg sacs

Stem heavily encrusted with scale