The Cottony Cushion Scale is a scale insect that feeds on over 65 families in the woody plant families, particularly Pittosporum and Citrus trees.
The scientific name of this pest is Icerya Purchasi or Icerya Purchasi Maskell, and it belongs to the family of Margarodidae.
These insect scale bugs are native to Australia.
This pest was described originally from the specimens gathered in New Zealand in 1878 as Kangaroo Acacia’s pests.
It threatened the southern California citrus industry for about ten years but now is found in numerous parts of the world.
In California, the new control methods were used for this scale and then in the other parts of the United States, which resulted in the implementation of integrated pest management, including biological control.
What Is The Cottony Cushion Scale Pest?
These scale insects have a protective covering which resembles a cotton texture, hence its common name.
The infestations are found attached to the stems and leaves of the plant.
There are four to five developmental life stages of the cottony cushion scale.
These scales are about 0.39″ inches long, with three pairs of black legs, and black antennae.
The adult females and nymphs have mouthparts to suck the contents directly from the cells of the plant.
The Icerya Purchasi typically sucks the sap of the plants, leaving the plants weak.
The sap includes a high amount of sugars and water, which is far more than what the insect needs.
As a result, these crawlers excrete all the excess content on the plant. This liquid is known as honeydew.
What Damage Does Cottony Scale Cause?
When the honeydew is left on the plant’s surface, the flowers and foliage form a sooty mold.
This gradually turns the leaves black, blocking the sunlight.
The higher the number of blackened leaves, the slower will be the plant’s growth.
The honeydew left behind by these mealybugs results in premature loss and yellowing of leaves.
Heavy infestations also destroy the young shoots of the plants.
How To Control The Pest Or Condition?
The best control of the Cottony Cushion Scale is through biological control.
Rodolia Cardinalis (ladybird species), Vedalia Beetle, Cryptochaetum Iceryae, and other imported Australian ladybird beetles are the main natural enemies of this scale.
Therefore, try conserving the mentioned enemies to prevent and control the infestation, without the use of chemicals.
The females and their eggs are protected by the cottony texture, which protects it from the insecticides.
Therefore, preserving its natural enemies is the best means of controlling the scale.
Be on a lookout for the Vedalia Beetle and its red eggs on top of the egg sac of the scales; leave the beetle to deal with the problem.
In case there aren’t any predators around, apply horticultural oil to the hosts when they are in a state of dormancy.
Spray insecticides on the foliage of the plant when the female scales are dead and the eggs hatch.
These young instars will soon spread rapidly if not controlled in a timely manner.
Another way of controlling the crawlers when they are hatching is by placing double-sided tape to trap them.
Encircle various branches and twigs near the eggs with the sticky tape and be sure to change the tape regularly.
Do this weekly till the infestation is eliminated.
Use the insecticides like Acephate or Organophosphates Malathion as a last resort since they are toxic to the scales’ natural enemies as well.
Avoid using Imidacloprid as it poisons Vedalia Beetles after they feed on the scales.
Eliminating the natural predators of the Cottony Cushion Scale might lead to a further outbreak of the scales.