Cottony Cushion Scale Identification Guide
Icerya purchasi
Cottony cushion scale is a sap-feeding insect known for its white, fluted egg sac and orange-red body. Originally from Australia, it now lives across North America on citrus and ornamental plants.
Taxonomy
Cottony Cushion Scale Coloration
Common color patterns to help identify cottony cushion scale
Cottony Cushion Scale
Seasonal Activity
When cottony cushion scale are most active throughout the year
Where Cottony Cushion Scale Are Found
Hover over states to see their names. Green regions indicate where cottony cushion scale have been reported.
Cottony Cushion Scale Identification Guide
Physical Characteristics
Cottony cushion scale (Icerya purchasi) is one of the easiest scale insects to spot on landscape plants. Adult females have an oval, orange to reddish-brown body about 5 mm (roughly 1/5 inch) long. They have black legs and antennae that are easy to see.
The most notable feature is the large, white, grooved egg sac that sticks out from the back of the body. This fluted, cottony structure can grow to 10 mm or more. With the egg sac included, the total length reaches about 15 mm (roughly 5/8 inch).
Bright red eggs show inside the egg sac when it is opened. Newly hatched crawlers are tiny, red, and very active. They have dark legs and antennae. As they grow, nymphs form a thin waxy coating and take on adult coloring. Males are rarely seen. They are tiny winged insects that live only long enough to mate.
Common Species
Only one species carries the common name cottony cushion scale in North America:
- Cottony cushion scale (Icerya purchasi Maskell): found across the southern United States and in warmer climates worldwide.
A few related Icerya and Crypticerya species live in tropical areas but are uncommon in most of North America.
Cottony Cushion Scale Behavior and Biology
Lifecycle and Reproduction
Females lay between 200 and 600 bright red eggs inside a grooved egg sac. After hatching, the tiny crawlers spread across the host plant. They settle on leaf veins, twigs, and branches. Once in place, they push needle-like mouthparts into the plant and start feeding on sap.
As they grow through two to three stages, the insects release waxy white threads. These threads form the cottony covering you see on infested plants. In warm areas like southern California or Florida, this pest can finish two to four generations per year. In cooler regions, expect one to two generations between spring and fall.
One unusual trait is that females can fertilize their own eggs. This is rare in the insect world. It means a single individual can start a new problem without mating.
Feeding Habits and Damage
Cottony cushion scale feeds only on plant sap. It attacks over 200 types of plants. Common targets include citrus, pittosporum, nandina, cocculus, acacia, and many woody shrubs and trees. Heavy feeding drains nutrients and water. This leads to yellow leaves, twig dieback, less fruit, and sometimes plant death.
As the insects feed, they give off honeydew. This is a sticky sweet liquid that coats leaves and nearby surfaces. Honeydew draws ants, which guard the scale in return for the sugary food. It also supports the growth of black sooty mold, a dark coating that blocks sunlight and adds stress to the plant.
Natural Enemies
Cottony cushion scale has a well-known place in pest control history. In the 1880s, it destroyed much of the California citrus crop. The vedalia beetle (Rodolia cardinalis) and a parasitic fly (Cryptochaetum iceryae) were then brought in from Australia to fight it. This program is still viewed as one of the most successful pest control efforts ever. Today, these predators remain the main control for cottony cushion scale where they are present.
Treatment Methods for Cottony Cushion Scale
Cottony cushion scale is a landscape and crop pest, not a household pest. Treatment focuses on protecting ornamental and fruit-bearing plants. The best results come from combining predator-based control with hands-on and chemical methods.
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Ant management: Ants that tend cottony cushion scale for honeydew guard the scales from predators. Using ant baits or sticky barriers on tree trunks can cut off this protection and help predators do their job.
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Horticultural oils: Dormant oil sprays applied in late winter can smother overwintering scale on trees that lose their leaves. During the growing season, lighter oils target crawlers and young nymphs. Always follow label directions and avoid spraying in extreme heat.
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Insecticidal soaps: These contact sprays work well on exposed crawlers and young nymphs. Soaps only kill insects they touch directly and leave no leftover residue, so repeat treatments may be needed while crawlers are still active.
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Pruning and physical removal: For smaller problems, cut off heavily infested branches and scrape or wash off visible scale insects. Throw away pruned material away from the garden.
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Systemic insecticides: For severe cases where other methods have not worked, systemic products applied as soil drenches or trunk injections can offer longer-lasting results. Use these only under guidance from a local extension office and follow all label rules, as they can affect other insects in the area.
Timing matters for all treatments. The crawler stage is the most exposed and easiest to treat, typically in late spring through summer.
References
Other Garden Pests
Explore other species in the garden pests family
Commonly Confused With
Cottony Cushion Scale are often mistaken for these similar pests
Where Cottony Cushion Scale Are Found
Hover over states to see their names. Green regions indicate where cottony cushion scale have been reported.
Common Questions about Cottony Cushion Scale
What does cottony cushion scale look like?
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Adult females have an orange to reddish-brown body about 5 mm long with black legs and antennae. Their most recognizable feature is a large, white, fluted egg sac that extends from the rear of the body. Including the egg sac, the insect can measure up to 15 mm (about 5/8 inch) in total length.
What plants does cottony cushion scale attack?
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Cottony cushion scale feeds on over 200 types of plants. Common hosts include citrus trees, pittosporum, nandina, cocculus, acacia, and many ornamental shrubs and trees. It can also infest some indoor houseplants.
Is cottony cushion scale harmful to humans or pets?
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No. Cottony cushion scale does not bite, sting, or pose any health risk to people or animals. It is strictly a plant pest. However, heavy infestations can seriously damage or even kill ornamental plants and citrus trees.
What is the sticky residue on my plant from cottony cushion scale?
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The sticky substance is honeydew, a sugary liquid excreted by the scale insects as they feed on plant sap. Honeydew attracts ants and promotes the growth of black sooty mold on leaves and nearby surfaces, which can further reduce photosynthesis and plant health.
How does cottony cushion scale spread?
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The tiny red crawlers (first-instar nymphs) are the primary dispersal stage. They move across the plant on their own and can also be carried by wind, birds, garden tools, or on infested nursery stock. Ants that tend the scales for honeydew may also help move crawlers.
What is the vedalia beetle and why is it important?
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The vedalia beetle (Rodolia cardinalis) is a small ladybug imported from Australia in 1888 to control cottony cushion scale. It is considered one of the greatest successes in biological pest control history and remains the most effective natural enemy of this scale insect today.
When is the best time to treat cottony cushion scale?
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Treatments are most effective when timed to coincide with crawler emergence, typically in late spring through summer. Crawlers are the most vulnerable life stage because they have not yet developed a protective waxy covering. Monitoring plants regularly helps you catch crawlers early.
With five years of hands-on experience in the pest control industry, George Schulz is a registered technician with the Virginia Pest Management Association and a proud third-generation professional in a family business that's been protecting homes for over 57 years. He manages and trains a team of service pros while also leading internal research efforts—recently spearheading a deep-dive review of thousands of documents on pest control materials to hand-pick the most kid and pet friendly, most effective solutions tailored specifically for homes in the DC metro area.