Cottony Cushion Scale
( Icerya purchasi )



Identification:Icerya purchasi
(Maskell ,1878 )
Common Name:Cottony Cushion Scale
Life Stage:(A) adult


Taxon Code:HOM01446

Location Name
Gardens at Lake Merritt, Lakeside Park, 666 Bellevue, Oakland
County:Alameda County
ECI Site#:CA01100110

The body of the female cottony cushion scale is orangish brown. Its most distinguishing feature is the elongated, fluted white cottony egg sac that is attached to its body. Its cottony egg sac and profuse honeydew production make cottony cushion scale easy to spot in the landscape.
Body Length
Female: Up to 12 mm, including egg sac.

Females of this insect live on top of their fluted, cotton-like egg sac, making them look like a tiny cushion. This prolific insect produces egg cases containing 600-800 eggs. The female’s body may be orange, yellow, or brown. Males are red, wingless and rarely seen. The insect occurs on citrus and other woody shrubs and trees. They weaken their host plants by sucking their phloem sap. Citrus production can be severely impacted when infestations are severe. The insect excretes copious amounts of honeydew, which is attractive to ants. Unlike most scale insects this species never loses its legs and retains its mobility throughout its life. Eggs hatch into crawlers that are red with black legs and antennae. They are most often seen along the veins of leaves. Later stages may move to other parts of the plant.
Common hosts in California are citrus, cocculus, nandina, and pittosporum, but may infest a number of woody ornamentals and crops.
In the 1800s it was a major pest of Citrus in the western United States it was a major pest of Citrus crops, but was controlled in 1889 by a beneficial lady beetle (Rodolia cardinalis). The control was so successful that in 1893 a Florida nurseryman asked for some of the beneficials to be sent to Florida, to test as a control for other scale insects. The scale was included in the shipment as food for the beetles and accidentally introduced to Florida citrus. Like other scales, cottony cushion scale decreases the vitality of its host by sucking phloem sap from the leaves, twigs, branches, and trunk. Feeding can result in defoliation and dieback of twigs and small branches when infestations are extremely heavy. Heavy populations can severely reduce the yield of citrus trees. Like soft scales, cottony cushion scale excretes honeydew, which is usually accompanied by blackish sooty mold growth and ants.
Native to Australia, has spread widely as a crop pest.
The insect is hermaphroditic producing sperm that can fertilize its own ova, but in an alternate reproductive strategy it can also make winged males that can fertilize the female part of other individuals. The white fluted egg sac that can contain up to 1,000 eggs. Eggs hatch into crawlers in a few days during warm weather but take up to two months to hatch in winter. Crawlers are red with black legs and antennae. They settle along leaf veins and begin to produce the white cottony secretion they are known for. At molts the scale leaves behind its white, cottony molting skin. Immature scales look reddish for a short period of time before they begin producing more cottony secretions. Second-instar nymphs settle on twigs and leaves, usually along leaf veins. Third-instar nymphs move to branches. Adults may be found on branches or on the trunk of trees. The minute red-winged male is rarely seen, and females do not need to mate to reproduce young. There are two to three generations a year. Unlike most other scales, it retains its legs and its mobility throughout its life. Cottony cushion scale completes its life cycle in three months during warm weather conditions.

Eddie Dunbar
Insect Sciences Museum of California

Species Icerya purchasi - Cottony Cushion Scale. ( Accessed May 30, 2016. .
Cottony Cushion Scale. ( Accessed May 30, 2016.