Cottony Cushion Scale

What it does

Females settle on twigs, branches, and leaf veins to suck sap, then secrete a distinctive ribbed white egg sac two to three times their body length. Mobile young crawlers spread to new growth. Heavy feeding drains vigor, yellows leaves, and drips honeydew that grows black sooty mold, dulling foliage.

Where it lives

Cottony cushion scale attacks citrus most notably, plus pittosporum, acacia, rose, boxwood, magnolia, and many ornamentals. It favors warm regions and is common in California, the Gulf Coast, Florida, and the Southeast, on landscape and orchard plants outdoors and in greenhouses.

How it breeds

Each hermaphroditic female produces hundreds of red eggs inside the cottony sac. Eggs hatch into crawlers that settle and feed, molting to adults. There are two to three overlapping generations a year in warm climates, so populations can build over a growing season if predators are absent.

What it eats

It feeds solely on plant sap from the twigs, branches, and leaves of its woody hosts. It does not damage structures or stored goods and poses no threat to food in the home.

Identification

The unmistakable feature is the white, fluted (ribbed) egg sac attached to an orange-brown, waxy female, together up to about 15 mm long, on twigs and leaf midribs. Young crawlers are reddish and tiny. The ridged sac separates it from smoother mealybugs and other scales.

Signs of an infestation

• White fluted, ribbed egg sacs on twigs and leaf veins
• Sticky honeydew on leaves and surfaces below
• Black sooty mold coating foliage
• Yellowing leaves and dieback on heavily infested branches
• Ants tending the colonies for honeydew

Prevention tips

• Inspect new nursery plants before bringing them home
• Protect and encourage vedalia beetles and lacewings
• Prune out and destroy heavily encrusted twigs
• Rinse light infestations off with a firm water spray
• Avoid broad-spectrum sprays that kill natural predators

Professional solutions

Cottony cushion scale is a classic biological-control success: the vedalia beetle and a parasitic fly usually keep it in check, so chemical sprays are often unnecessary and can backfire by killing those predators. For heavy cases, horticultural oil applied to crawlers per label, or professional advice, is preferred.