Cottony Cushion Scale

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Summary

Icerya purchasi, known as the cottony cushion scale, is a significant agricultural pest that originally hails from Australia. It is noted for its unique reproductive strategy and has been the focus of successful biological control measures.

Physical Characteristics

Mature hermaphrodites are oval in shape, reddish-brown with black hairs, measuring about 5 mm in length. The white fluted part is an egg sac that can contain up to 1000 eggs. They retain legs and have limited mobility in all life stages.

Identification Tips

Identified by the white cottony egg sac on infested plants, which is a main characteristic of the species.

Habitat

Infests mostly twigs and branches of various woody plants, particularly in citrus orchards and other relevant environments where host plants grow.

Distribution

Native to Australia, now found worldwide where citrus crops are grown, particularly in the US, alongside the Atlantic seaboard and in California.

Diet

Feeds on the sap of over 80 families of woody plants, notably Citrus and Pittosporum.

Life Cycle

The lifecycle stages include egg, nymph, and adult, with nymphs being the primary dispersal phase. Their life cycle is temperature-dependent, taking longer in cold temperatures and shorter in warmer conditions. They retain legs throughout their life stages allowing some movement.

Reproduction

Hermaphroditic species that can self-fertilize. Males are rare, while females can produce both sperm and eggs. Diploid offspring are produced internally through hermaphroditism. Rare true males are known for mating, resulting in mixed offspring of males and hermaphrodites.

Predators

Natural predators include the vedalia ladybird beetle (Rodolia cardinalis) and the parasitic fly Cryptochetum iceryae, which have been used for biological control.

Ecosystem Role

As a sap-sucking pest, it plays a significant role in pest dynamics within agricultural ecosystems and supports a food web including predatory species.

Economic Impact

Historically recognized as a major pest of citrus crops, leading to significant economic losses, prompting extensive biological control measures.

Collecting Methods

• Sampling infested plants
• Visual inspection for egg sacs and adults

Preservation Methods

• Drying
• Alcohol preservation

Evolution

No specific evolutionary data provided in the text, but hermaphroditism suggests a potential evolutionary adaptation to conditions where mates are scarce.

Similar Taxa

• Other scale insects in the Coccoidea superfamily

Misconceptions

Commonly thought to be limited to citrus, but it infests a wide range of woody plants.

Tags

• Cottony Cushion Scale
• Icerya purchasi
• Agricultural Pest
• Biological Control