Mealybugs on cacti can be a pesky problem for any plant owner. These small, white insects can damage and weaken the plant by sucking the sap from its leaves, stem, and roots. In this guide, explore effective ways to keep your cactus mealybug-free.
The British Cactus and Succulent Society says mealybugs are among the worst plant pests. You need to remove mealybugs as soon as you notice them; they reproduce and spread quickly, and controlling them in large colonies can be difficult.
Two major types of mealybugs can affect cacti and other indoor plants. They include the common mealybugs that infest the plant foliage and the root mealybugs that dwell in the soil and feed on plant roots.
Root mealybugs are the most difficult to control since they live below ground. They can silently kill a plant by damaging its root system. The only way to tell if your plant is infested is to remove it from the soil and inspect the roots.
Signs of mealybugs on cactuses
A fluffy white stuff fuzz on succulent leaves or stems signifies mealybugs. The cottony white substance is where females nest and lay eggs. At first, it can be difficult to notice them from a distance, as they like hiding under the leaves or tight areas of the plant.
Mealybugs and scale insects on cacti will always target new growth. They create openings in a succulent as they suck sap and juices. This exposes the plant to bacterial and fungal infections. The affected plant may not survive for long.
If your cactus is turning yellow, wilting, not growing, or showing unusual spots may also indicate a pest problem. The first thing you should do when you suspect mealybugs is to inspect all your plants thoroughly.
Look at the newly grown stems around the substrate and lower side of the plant leaves. Quarantine the affected plant and immediately launch a control strategy.
How to get rid of mealybugs on cactus
There are several nonchemical ways to deal with mealybugs. You can pick on one of the following:
1. Use rubbing alcohol
Rubbing alcohol is highly effective against mealybugs, spider mites, and scale and aphids. 70% Isopropyl Alcohol applied at full strength will penetrate the bugs’ bodies and dry them from the inside, instantly sending them to their demise.
Spray the alcohol directly in the white fizz or apply using a cotton swab, cotton ball, or soft cloth.
To completely kill all the bugs, you must apply the alcohol more than once. Be sure to check your plants every two weeks and apply the treatment if needed. Avoid spraying in direct sunlight, as it can cause burns.
2. Apply soapy water
Soaps are known to kill many insects on houseplants, including mealybugs. They are substantially less expensive and readily available. However, there is a risk of plant injury, explains Scott Oneto, Farm Advisor, University of California Cooperative Extension.
Using soap sprays that are diluted more than suggested on label instructions can help reduce plant injury. Simply mix one tablespoon of dish soap and 1 gallon of water and use a spray bottle to apply directly to cover the target insect.
Since soaps have little or no residual action, you must regularly apply them until all the pests are gone.
Several insecticidal soaps in various brands are available over the counter, and you can use them safely to control plant bugs. Although they are chemically similar to most household detergent soaps, they are formulated to minimize potential plant injury. Be sure to use as directed on the label.
3. Make neem oil spray
Neem oil is a naturally occurring insecticide highly effective against mealybugs and many other insects. The oil is extracted from the Indian neem tree seeds and is either sold in its pure form or mixed with other ingredients to form pesticide sprays.
Neem oil repels, smothers, and also kills insects on contact. To use, Put 2 teaspoons of neem oil concentrate, 1 teaspoon of mild liquid soap, and 1 liter of distilled water in a spray bottle and shake to mix well.
Douse every part of the cactus with the solution, including the leaves bottom. Keep the plant out of direct sunlight until the leaves are dry.
Neem oil has a small residual effect; therefore, continue to apply it every few weeks until all the mealybugs are gone. Adding soap to the neem oil makes it mix well with water. Additionally, soap kills plant pests on contact, making the solution more effective.
Pro Tip: When I mix neem oil and insecticidal soap, the results are always amazing as compared to when I use each separately.
NOTE: Neem oil has a strong scent; if you haven’t used it before, it might feel uncomfortable. However, the smell goes away once the spray dries. The oil can also stain your fabrics, including the carpet. Therefore, use it on a hard surface where you can easily clean it.
4. Encourage natural predators
You can encourage or introduce natural predators in your garden to help combat the problem of mealybugs. The ladybug species Cryptolaemus montrouzieri commonly referred to as the mealybug destroyer, is known for feeding on mealybugs greedily.
Lacewings, parasitic wasps, and pirate bugs also feed on mealybugs.
Mealybugs excrete honeydew, a sugar substance that attracts ants. Ants around mealybugs will definitely discourage natural predators. You will need to find a way of discouraging ants if you want to introduce beneficial insects into your garden.
Tilling your garden and destroying the ant nests can send them away. You can also provide alternative nectar sources for the ants. Do not use a pesticide on the ants; it will also kill the mealybug predators.
5. Use diatomaceous earth
Diatomaceous earth kills a wide range of pest insects, including mealybugs. When applied to insect pests, this powder-like substance penetrates their bodies, causing them to dry and die. You’ll need to make multiple applications to achieve the desired results.
Diatomaceous earth is natural and safe for both plants and animals.
Mealybugs infest plants for food, and in the process, they nest and reproduce. It is easier to prevent them on your indoor plants than outdoor ones. When purchasing a new plant, ensure to inspect it thoroughly for signs of white mealybugs.
Further, isolate your newly acquired plants for one week before mixing them with the others.
- “Mealybugs in Greenhouses,” UMass Extension Greenhouse Crops and Floriculture Program
- “Mealybugs,” Karen Delahaut, formerly UW-Madison Fresh Market Vegetable Program
My name is Diane M Lewik, and I am the founder of this website. I am a degree holder in plant biology from the University of California – Berkeley. Over years, I have cultivated a vast collection of succulents and I have learned a great deal about how to grow and care for these unique plants.