Cottony Cushion Scale – Icerya purchase

Cottony cushion scales/ Mealybugs/ woolly Adelgids

What are cottony cushion scales?

Cottony Cushion Scales (Icerya purchasi Maskell) are an insect with delicate scales. The hundreds of white waxy egg bags that adult females attach to their bodies give them their name and look.

The life cycle of Cottony Cushion Scales:

Female cottony cushion scales are rusty red with black legs and antennae. They are roughly 4.5mm long. The mouthparts are of the piercing/sucking kind. Male cottony cushion scales are tiny (3mm) reddish-purple insects with two metallic blue wings. The ovisac has reddish oval eggs and is fluted with 14 to 16 ridges. Tiny initial nymphs are scarlet with black legs and antennae. Second, nymphs are often coated with wax and fine hairs. They are around 18 inches long.

Damage of Cottony Cushion Scales:

Cottony Cushion Scales infected plants frequently become covered with honeydew, a sugary liquid produced by the bugs. They can weaken plants, leaving them more vulnerable to borers or ecological extremes, and they can induce leaf and needle stunting and yellowing, twig and branch dieback, and even mortality. Cottony cushion scales are frequently mistaken for Mealy Bugs.


Cottony cushion scale control by vedalia beetle


The vedalia beetle best controls the cottony cushion scale. Vedalia beetles reproduce quickly (they may complete four generations in the time required cottony cushion scale to complete one) and devour a significant number of cottony cushion scale eggs and nymphs in a short period. When vedalia beetles arrive in an orchard, they may eliminate a major cottony cushion scale infestation in 4 to 6 weeks.

Chemical control of cottony cushion scale:

When the scale consumes the sap, they swallow the poisonous pesticide and die. Three widely used systemic pesticides that are effective against scale include acephate, imidacloprid, and dinotefuran. The combined pesticide is poured at the base of the plant as a treatment. Scale insects can be killed by wiping them with a cotton swab bathed in rubbing alcohol, which is a sure but time-consuming approach. As long as you are diligent, this is completely effective. Another method for killing mealybugs and cottony cushion scale is to use hot water.

What are Mealybugs?

Mealybugs are around 3-7mm long and inflict harm comparable to aphids, such as deformed leaves, weakening plants coated with glossy honeydew, and sooty mold. Mealybugs are coated in a whitish’mealy’ wax, which aids in the retention of water in their soft bodies. They enjoy warm, humid, protected environments free of severe climatic conditions and natural adversaries.

Life Cycle of mealybugs:

Mealybugs are insects that deposit eggs yet bore live offspring in the same way that aphids do. The female dies after laying eggs for five to ten days, while the male dies after depositing eggs for five to ten days. Young female mealybugs have three instars (stages) and are mobile throughout their lives. Adult males are small and winged, although they are rarely observed and live for a few days.

Mealybug Damage:

Mealybugs cause yellowing, stunted growth, galls, and dieback by draining sap from plants. They also exude sweet honeydew, which attracts Wasps, Ants, and Bees and can serve as a substrate for the growth of Sooty Mold (link). Immature Mealybugs are highly busy, traveling all over a plant looking for the best feeding location. They grow less energetic as they age, moving around very little.


 Non-Chemical control of mealybugs:

Prevention is the most effective mealybug control strategy. Upon delivery, all new plant material should be examined, and any infected plants should be returned to the supplier. Destroy highly infected greenhouse plants since cleaning them up will be difficult, if not impossible, and very expensive. To avoid an alternate infection location, remove any extra soil and compost piles from the growing area.

Chemical control of mealybugs: 

Mealybugs can be controlled using a variety of pesticides. Contact sprays containing insecticidal soaps are effective against the mealybug crawler stage if thoroughly applied. When helpful insects are found, use insect growth regulators. To get excellent control, you will need two to three treatments spaced 10-14 days apart.

What are Hemlock Woolly Adelgids?

The hemlock woolly adelgid, or HWA, is an invasive, aphid-like bug native to Asia that affects North American hemlocks. HWA is very little (1.5 mm) and frequently difficult to detect, but they may be distinguished by the white fuzzy masses they produce on the underside of branches near the base of the needles.

Life Cycle of Hemlock woolly Adelgids:

In northern North America, all hemlock woolly adelgids are female. Egg-laying begins in early April before the first wildflowers emerge. In March, little reddish-brown nymphs (also known as crawlers) hatch from clusters of up to 300 eggs and either scatter from the tree or settle around the base of the needles. The crawlers have a characteristic white fringe around their flanks, which is secreted later.

How HWA Damage Trees:

Crawlers, or juvenile HWA, look for appropriate locations on the host tree, generally near the base of the needles. They insert their lengthy mouthparts and begin eating on the stored carbohydrates in the tree. HWA dwell in the same location for the duration of their lives, eating and growing into adults. Their eating causes significant harm to the host tree’s canopy by interrupting the flow of nutrients to its twigs and needles. Tree health deteriorates, and death happens between 4 to 10 years.


Biological Control of Hemlock woolly Adelgids:

The HWA arrived from Asia with no natural adversaries to keep numbers in control in its native habitat. Furthermore, it eats throughout the colder months of the year, when our main predators are still dormant for the winter. An effective biological control campaign in New York will necessitate the development of several predators, such as those seen in HWA’s natural habitats. Several Asian predators have been studied, authorized, and successfully introduced across the HWA range in the eastern United States.

Chemical Control of Hemlock woolly Adelgids:

Chemical pesticides can be used to treat a tree already infected or as a preventative step in a high-risk infestation region. They’re beneficial for treating individual, decorative, or high-value trees, but they’re neither feasible nor cost-effective in a forest environment. Imidacloprid and Dinotefuran are two insecticides that have demonstrated promising effects. Both must be administered by a qualified pesticide applicator and are capable of killing HWA on their own. When both insecticides are applied to an infected tree, the instant efficacy of the fast-acting Dinotefuran is combined with the long-term protection of Neonicotinoids, leaving the tree adelgid-free for up to seven years.