Cottony Cushion Scale
Icerya purchasi
📖 Description
The cottony cushion scale is one of the most recognizable scale insects due to its large, white, cottony egg sac that extends dramatically from its body. This insect has a storied history in entomology — it nearly destroyed the California citrus industry in the 1880s before being controlled by the introduced vedalia beetle, marking the first successful biological control program in the world. Today, it remains a serious pest of citrus and many ornamental plants, particularly in warm climates. Heavy infestations can kill branches and even entire young trees through sap depletion and sooty mold growth that blocks photosynthesis. The egg sacs contain hundreds of eggs and are the most conspicuous sign of infestation, often appearing in large numbers along stems and branches.
⚠️ Symptoms to watch for
- White, cottony egg sacs protruding from stems and branches,Black sooty mold growing on honeydew-coated leaves,Yellowing leaves and branch dieback,Sticky honeydew on surfaces below infested plants,Reduced vigor and stunted growth in young trees,Severe defoliation and branch death in heavy infestations
🩹 Treatment
- Release vedalia beetles (Rodolia cardinalis) for biological control (organic),Apply horticultural oil during crawler stage in spring (organic),Scrape off visible scales with a soft brush (organic),Spray with insecticidal soap targeting crawlers (organic),Apply systemic imidacloprid as soil drench (chemical),Use dinotefuran trunk spray for established trees (chemical)
🌿 Organic treatments
- Release vedalia beetles (Rodolia cardinalis) for biological control,Apply horticultural oil during crawler stage in spring,Scrape off visible scales with a soft brush,Spray with insecticidal soap targeting crawlers
🧪 Chemical treatments
- Apply systemic imidacloprid as soil drench,Use dinotefuran trunk spray for established trees
🛡️ Prevention
- Inspect new plants thoroughly for white cottony masses before purchasing,Encourage natural predators like vedalia beetles and ladybugs,Maintain plant health with proper watering and nutrition,Prune and destroy heavily infested branches,Quarantine new citrus and ornamental plants before adding to garden,Monitor for crawlers in spring when they are most vulnerable to treatment
🪴 Affected plants
- Citrus Trees,Pittosporum,Acacia,Rosemary,Nandina,Oleander,Wisteria
🦋 Natural predators
- Vedalia Beetles,Parasitic Wasps
🌱 Host plants
- Citrus spp.,Pittosporum spp.,Acacia spp.
🔄 Lifecycle
- Females produce an elongated white egg sac containing 600-800 eggs over 1-2 months.
- Eggs hatch in 1-2 weeks depending on temperature.
- Crawlers settle along leaf veins and stems, feeding on sap.
- Nymphs pass through 3 instar stages over 4-6 weeks before maturing.
- Females begin producing egg sacs within 1-2 weeks of maturation.
- Two to three generations per year in warm climates, one in cooler regions.
- Adult females can live 2-3 months and produce multiple egg sacs.
📅 Season
- Year-round in warm climates, Spring to Fall in temperate zones
🔎 Appearance
- Adult females are distinctive with an elongated, deeply grooved white cottony egg sac that extends far beyond their body, often 2-3 times their body length.
- The body is reddish-brown with a white, waxy coating.
- Without the egg sac, they are oval and segmented.
- Males are tiny, red, winged insects rarely seen.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Australia
- South Africa
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