Scale insects on houseplants – how to combat them at home

An inconspicuous insect, a motionless plaque on a houseplant, may initially appear harmless, but in reality, it can cause significant damage even when discovered. Scale insects on houseplants, the damage seen in the photo, are a real scourge that requires careful management and prevention.

Indoor plants are infested with scale insects

Scale insects belong to a vast family of hemipteran insects. Of the diverse range of species (over 2,000), only a few dozen prefer to parasitize houseplants.

Depending on their developmental stage, they exhibit varying activity and vulnerability. These pests have adapted well to living off plants.

Characteristics of the parasite

All species in this family have protective waxy shields on their bodies, varying in shape, size, and color. These shields are not part of their body (compared to false scale insects). In captivity, scale insects prefer to feast on citrus fruits, palms, and bromeliads (orchids).

The female has an oval or rounded, flat, brown, reddish, or almost black scutellum (the color is a species-specific characteristic and may vary), reaching 5 mm in length. The body beneath the scutellum is white or pale brown, 1.5-2 mm long. Legs, wings, eyes, and antennae are absent. Only powerful, piercing-sucking mouthparts are present.

Males are smaller. They are elongated, with a small shield, often white and pubescent, but can also be light orange, reddish-gray, and so on. They lack mouthparts, but they have eyes and well-formed limbs, as well as wings. They are mobile, even capable of flight, but their lifespan is short (a few days), and they die after mating.

Females live up to four months, motionlessly covering their young on the plant. The insect undergoes parthenogenesis (females reproduce without the participation of males). The eggs are extremely small—0.1-0.3 mm—oval or oblong-oval, white, then light gray, and then light brown.

Young yellowish larvae, up to 0.3 mm long, are nicknamed "vagrants" because they nimbly wander around the plant in search of food on their three pairs of legs. They usually transform into females, settling in any convenient location, losing mobility, and developing a waxy shield.

Parasites are especially active and voracious during the winter period, when plants are weakened and their metabolism is disrupted due to improper care.

External signs presence of a pest

Within a few hours of hatching, the larvae begin actively consuming plant juices, primarily targeting the undersides of leaves. Adults can be detected with the naked eye by the presence of spots (plaques) on the stems and leaves.

Small young plants are difficult to spot, but a magnifying glass can help you spot their active movements. If you don't notice them in time, their presence will be indicated by honeydew (a sticky liquid). This is a favorable environment for the development of sooty mold. The overall result is drying out, leaf drop, and death of plant parts.

Where does parasite come from in the house?

Scale insects are found indoors through infested purchased and gifted plants, specimens dug up from open ground, and garden soil. The parasites are sometimes carried in through a window by the wind.

The harm of the parasite to indoor plants

Scale insects cause damage by sucking out the cellular sap of plants. As a result, leaves turn yellow or brown, curl, and fall off, shoot growth is stunted, and flowers dry out and eventually die.

How to fight scale insects?

If a dangerous pest is detected, it is advisable to immediately isolate the plant and inspect all nearby flowers. The choice of further control methods depends on the extent of the infestation.

Chemicals and processing rules

If it is not possible to get rid of the pest mechanically, then insecticides have to be used. It should be noted that females and their egg-laying areas are well protected by shields, so it is unlikely that they will be controlled with a single treatment.

You can use the following tools:

1. Fitoverm is biologically derived and therefore less dangerous to humans and pets than some other chemical treatments. This insecticide and acaricide acts by stomach and contact. Dissolve 2 ml of Fitoverm in 200 ml of water and spray the affected plant. Three to four treatments, spaced 5 to 8 days apart, should be sufficient for the desired result. To strengthen the plant, applying Epin (a growth stimulant) at the end of the treatment can be helpful.
2. Confidor is a systemic and contact pesticide. Despite its effectiveness (it lasts 15-30 days on pests), it is considered moderately hazardous to animals and humans. Dissolve 1 g of Confidor in 0.5 liters of water (4 ml per 10 liters), then spray the plant and soil.
3. Aktara is a stomach-contact insecticide that, when applied to foliage, is effective for 2 to 4 weeks. For spraying, prepare a solution of 1 g of the product per 1.25 liters of water (warm, at least 25°C), and for soil irrigation, mix 1 g per 10 liters. It penetrates the leaves through the roots and blood vessels, making them toxic to pests. The interval between 2-4 treatments is 10-12 days. To prevent insect tolerance, this product can be alternated with other products.
4. Actellic is a potent, broad-spectrum organophosphorus insecticide and acaricide. It's highly toxic, making it a lifesaver in difficult situations. Two to three treatments (every three days) are sufficient. You'll need 2 ml of the product per 1 liter of water.

To combat scale insects, you can also use Avantpost and Advantix drops, which are used to rid indoor dogs and cats of fleas, lice, and ticks. Dilute a small capsule in 0.5 liters of water, and a larger one in 1 liter. Then, apply the drops to both sides of the leaves, as well as the axils, stems, petioles, and even the soil. A single treatment may be sufficient. If the infestation is extensive, repeat the treatment after a week. It is recommended to perform the treatments outdoors: outdoors or on a balcony.

Traditional methods and prevention

The key to success with traditional methods is careful preparation. Their main advantage is their eco-friendliness. Various remedies are popular:

1. Soapy solution. Wipe all leaves and stems individually with a cotton pad, sponge, or the soft bristles of an old toothbrush soaked in a solution of tar, laundry soap, or green potassium soap. It's best to temporarily cover the soil. After 2-4 hours, rinse off the foam with hot water (up to 50°C). Some believe this solution clogs pores and disrupts photosynthesis.

   

   

2. Vinegar. Dilute the product in water to make the solution slightly acidic, then wipe and spray the affected area.
3. Garlic, onion, hot pepper, and tobacco infusions. Individually crushed ingredients are steeped in 0.5 liters of water (5 cloves of garlic – 1-2 days, 1 onion – 2-3 hours, 50 g of pepper – 1 day, 80 g of dry tobacco – 1 day), strained through cheesecloth, and used for spraying or wiping. Tobacco and pepper infusions are diluted in 1 liter of water.
4. Oil (olive, sunflower, machine, neem). Whip 10-15 g of soap in a glass of water until foamy, mix 2 tablespoons of sunflower and olive oil (or 15-20 ml of machine oil), rinse the plant completely with the resulting liquid, and rinse after 6-9 hours.

   

   

   Neem oil is used as a biological control agent for many insects, including, of course, scale insects. Simply apply it to a cotton ball and apply it to all parts of the plant. Some experienced gardeners swear by this treatment's effectiveness. It can also be used simply as a preventative measure.

5. Kerosene. Add 5 drops of kerosene to a soap solution (40 g of soap and 1 liter of water), shake well, and then spray or wipe the scale insects' habitat.
6. Alcohol. As with kerosene, add any alcohol or vodka to a soap solution (1 tablespoon of soap shavings per 1 cup of water), then dilute with water (300 ml). To avoid burning the flower, rinse with warm water 10-15 minutes after treatment. Alcohol and kerosene can damage delicate plants.

Prevention is key to keeping your green pets safe. Preventative measures include:

• quarantine of new plants;
• washing hands before contact with the flower;
• maintaining hygiene in areas where flower containers are located;
• regular inspection, it is especially important to examine the underside of the leaves (it is better to use a magnifying glass);
• ventilation and spraying;
• moderate watering;
• Seasonal feeding to strengthen plant immunity.

It is not recommended to replant a plant with scale insects.

Frequently Asked Questions

Gardeners strive to protect their flowers from pests. When scale insects appear, there's little time to think. Action is needed immediately, otherwise they will destroy everything. But first, it's important to know how to fight them, what to use, and how to prevent further dangerous infestations.