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How to Get Rid of Scales on Cosmos Plant

Updated: March 24, 2022

Cosmos plants are beautiful and easy to grow, but they are not immune to pests. One of the most common pests that affect cosmos plants is scales. Scales are small, flat insects that attach themselves to the stems and leaves of plants and suck the sap out of them. They can quickly multiply and cause serious damage to the plant if left untreated. In this article, we will discuss how to get rid of scales on cosmos plants.

Identify the Scale Insects

Before you can effectively treat scales on your cosmos plant, you need to identify the type of scale insect that is infesting it. There are two types of scale insects: armored scales and soft scales. Armored scales have a hard, waxy shell that protects them from predators and pesticides. Soft scales do not have this protective covering and are easier to kill.

To identify scale insects on your cosmos plant, look for small bumps or lumps on the stems, leaves, or flowers. These bumps can be white, brown, or black in color, depending on the species of scale insect. You may also notice a sticky substance on the plant’s surface, which is a sign that the scales are excreting honeydew.

Treat the Infestation Naturally

If you prefer a natural approach to pest control, there are several methods you can use to get rid of scales on your cosmos plant:

1. Neem Oil

Neem oil is a natural pesticide that is safe for humans and pets but deadly to insects. To use neem oil to treat scales on your cosmos plant, mix two tablespoons of neem oil with one gallon of water and spray the solution onto the affected areas of the plant. Repeat this process every two weeks until the scales are gone.

2. Rubbing Alcohol

Rubbing alcohol is another effective natural remedy for treating scale insects. Mix one part rubbing alcohol with one part water and apply the solution to the affected areas of the plant with a cotton swab or spray bottle. The alcohol will dissolve the protective coating of the scales, causing them to die.

3. Horticultural Oil

Horticultural oil is a natural insecticide that is made from petroleum or vegetable oil. It works by suffocating the scales and preventing them from breathing. To use horticultural oil, mix two tablespoons of oil with one gallon of water and spray the solution onto the affected areas of the plant. Repeat this process every two weeks until the scales are gone.

Use Chemical Insecticides

If natural remedies do not work, you may need to use chemical insecticides to get rid of scales on your cosmos plant. However, it is important to choose a pesticide that is safe for your plant and does not harm beneficial insects like bees and butterflies.

1. Systemic Insecticides

Systemic insecticides are absorbed by the plant and kill the scales when they feed on it. These insecticides are effective but can take several weeks to work. They also remain in the plant’s system for a long time, so you should avoid using them if you plan to harvest the flowers or leaves.

2. Contact Insecticides

Contact insecticides kill scales on contact and are fast-acting. However, they can also harm beneficial insects and may require multiple applications to be effective. If you choose to use a contact insecticide, make sure to follow the instructions carefully and wear protective clothing.


Can scales kill my cosmos plant?

Yes, scales can cause serious damage to your cosmos plant if left untreated. They feed on the sap of the plant and can weaken it over time, making it more susceptible to other pests and diseases.

How do I prevent scale infestations on my cosmos plant?

The best way to prevent scale infestations is to keep your cosmos plant healthy and well-maintained. Make sure it receives adequate water and nutrients, and prune any dead or damaged branches regularly. You can also use natural remedies like neem oil or horticultural oil as a preventative measure.

Are chemical insecticides safe for my cosmos plant?

Chemical insecticides can be effective in treating scale infestations, but they can also harm your cosmos plant if used improperly. Always read the label carefully and follow the instructions closely to avoid damaging your plant.