Scale Control

How to Get Rid of Scale Insects Naturally

Scale insects are among the most difficult pests to control in the garden, greenhouse, landscape, and orchard. It's also one of the most commonly mismanaged. Their protective waxy coating shields the insect beneath from most contact treatments.

NaturesGoodGuys offers natural scale insect control solutions. Specialist predatory beetles and parasitoid wasps control scale insects naturally.

What Are Scale Insects?

Scale insects are tiny, sap-feeding insects in the superfamily Coccoidea, order Hemiptera. With 6,000 to 8,000 species worldwide, scale insects are one of the most diverse groups of plant-feeding insects on earth.

The two most economically important groups of scale insects are armored scale and soft scale. Understanding the difference and what scale insects look like is essential for choosing the right management approach:

Armored Scale (Family Diaspididae)

Armored scales are the smaller of the two groups, typically 1 to 3 mm, and the most challenging to control. Their defining characteristic is a hard, flat, protective cover (the 'armor') made of wax. The insect secretes the wax and combines it with shed skins from earlier instars to create the armor.

Do NOT produce honeydew: Unlike soft scale, armored scale insects do not excrete honeydew. If you see sticky residue or sooty mold, you are dealing with soft scale, mealybugs, aphids, or whiteflies, not armored scale.
Damaging common species include: California red scale (Aonidiella aurantii), San Jose scale (Quadraspidiotus perniciosus), oystershell scale (Lepidosaphes ulmi), euonymus scale (Unaspis euonymi), pine needle scale (Chionaspis pinifoliae), oleander scale (Aspidiotus nerii), and cycad scale

Soft Scale (Family Coccidae)

Soft scales are generally larger and more rounded or convex than armored scales, growing up to 1/4 inch long.

Produce honeydew: Honeydew buildup causes sooty mold on leaves. It also attracts ants that protect scale colonies from natural enemies. Wash heavy honeydew deposits from plants before you release biological control agents, because honeydew impedes beneficials’ movement.
Damaging common species include: Brown soft scale (Coccus hesperidum), black scale (Saissetia oleae), European fruit lecanium (Parthenolecanium corni), cottony cushion scale (Icerya purchasi), hemispherical scale (Saissetia coffeae), and magnolia scale (Neolecanium cornuparvum)

Signs of a Scale Infestation

Visual Signs on the Plant:

Small circular, oval, or oyster shell-shaped bumps on stems, bark, leaves, or fruit. Color can range from grayish-white to brown, yellow, or orange depending on species.
A 'crusty' or rough texture on stems and branches. Heavily infested stems can be encrusted wall-to-wall with scale covers, making the surface appear corky or diseased.
Yellowing, stippled, or bronzed leaves from sap removal and feeding toxins injected into plant tissue.
Leaf drop, stunted growth, or die-back of branches
Waxy, cottony white masses on stems, in leaf axils, or at the base of plants is a sign of mealybugs or cottony cushion scale

Indirect Signs:

Sticky honeydew deposits on leaves and surfaces below the plant (soft scale and mealybugs only)
Ants are often present because they tend soft scale for honeydew. They also protect them from predators and parasitoids.
Black Sooty mold (black, powdery fungal growth on leaves and stems) always means honeydew-producing pests are active above.

Scale Insect Life Cycle

Eggs: Eggs are laid under the protective cover of the mother scale. Armored female scale typically lay fewer than 100 eggs over their lifetime; soft scale females can lay over 1,000 eggs. Some species bypass the egg stage entirely and give birth to live crawlers directly (viviparity).
Crawlers (first instar nymphs) The Critical Window: The crawler stage is the only mobile life stage in females. They emerge from beneath the mother's cover and immediately begin seeking a suitable feeding site. Once a crawler settles and inserts its mouthparts, it quickly starts secreting a protective waxy cover.
Settled Nymphs and Adult Females: After settling, female crawlers lose their legs (armored scale) or become nearly immobile (soft scale). They develop through one to two more nymphal instars, and begin secreting their full protective covering. The scale you see on a plant is this protective coating.
Adult males: Adult males are winged (or wingless in some species), short-lived, and rarely seen. Their only function is mating. They do not feed. Adult males are occasionally confused with parasitoid wasps.

Scale & Ants: The Hidden Partnership

Ants often “farm” scale insects for their honeydew and will protect them from predators. If ants are present, your efforts to control pests with beneficial insects may not work as well. Managing ants can greatly improve the success of biological pest control.

Cultural Strategies

Avoid excessive nitrogen fertilization
Prune heavily infested branches
Inspect all incoming plants
Avoid overwintering scale insects on plants indoors

Physical / Mechanical Control

Monitoring for Crawlers: Wrap transparent double-sided tape around infested stems or branches. Active crawlers walking across the stem will stick to the tape.
Manual Removal – Rubbing Alcohol: For light infestations on houseplants or small shrubs, dab scale insects with a rubbing alcohol on a cotton swab.
Manual scrubbing: Use a soft toothbrush dipped in soapy water to scrub scale insects from stems, bark, and larger leaf surfaces. Rinse the plant thoroughly after scrubbing.
Beneficial Insect Netting to keep beneficial insects while keeping out harmful ones.
Diatomaceous Earth to create unfavorable conditions for soft-bodied pest insects.

Biological Control

Scale insects have a rich complex of natural enemies, and biological control is one of the most effective long-term strategies for scale management.

General Predators

Insects like green lacewings, ladybugs and Orius target their prey by eating pests whole or extracting body fluids.

Ladybugs are one of the most popular beneficial insects for pest control. Both adult and larval stages target scale crawlers, young nymps, and, for smaller scale species, adult soft scale.
Green Lacewing Larvae are aggressive predators of scale crawlers. They are particularly useful in greenhouse environments.
Orius insidiosus (Minute Pirate Bug) are highly agressive generalist predators that have high mobility to target scale crawlers.

Specialized Scale Predator - Lindorus lophanthae

(Scale Destroyer Beetle)

Lindorus lophanthae (also known as Rhyzobius lophanthae) is the most powerful specialist predatory lady beetle. Predatory in both the adult and larval stage, it attacks both armored scale and soft scale at all life stages.

Targeted Scale Control Aphytis melinus

(Armored Scale Parasitoid Wasp)

Aphytis melinus is a tiny parasitoid that is known as the most important parasitoid of California red scale. People also recognize it as one of the most commercially successful biological control agents for armored scale insects worldwide.

Soft Chemical Control

You can often manage light infestations with monitoring and releasing beneficial insects early. For moderate infestations, use a combination of beneficial insects and targeted treatments. Severe infestations need soft chemical knockdown for pest treatment, then a release of beneficial insects to prevent re-infestation. We offer gentle chemical solutions, including: