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There are over 1,000 species of mealybugs, a type of insect resembling small white moths or scale insects. They tend to gather in large numbers on the undersides of plant leaves. Both the larvae and adult mealybugs damage plants by feeding on their sap and spreading diseases. Once mealybugs have heavily infested a plant, it becomes extremely difficult to eradicate them. Multiple methods may need to be applied over several weeks, and in some cases, pruning the plant may be necessary.
Steps to Follow
Using Natural Solutions
Vacuuming Mealybugs. Use a handheld vacuum cleaner or the nozzle of your regular household vacuum to suck up mealybugs. Move around the infected plants and vacuum up the pests from the undersides of the leaves and the tree canopy. This method is quick, direct, and eliminates all stages of the mealybug lifecycle, from larvae to adult insects that feed on the plants. Vacuuming works best when done immediately upon noticing the infestation.
- Dispose of the vacuum bag when it's full of mealybugs. Place the vacuum bag in a plastic trash bag, tie it securely, and freeze it for at least 24 hours to kill the insects. Once all the mealybugs are dead, you can throw the trash bag in the regular garbage.
Remove Severely Infected Branches and Leaves. Use pruning shears to trim away as much of the infected plant material as possible, without harming the plant's overall health. You can also manually remove leaves affected by mealybugs. Look for white eggs and wingless "crawler" insects on the undersides of the leaves. Severely infected leaves may be coated in a sticky, waxy substance— a sugary secretion produced when the larvae suck plant sap. These leaves may also appear discolored and wilted.
- Only trim as much as necessary to maintain the plant's health. For weak plants infected with mealybugs, remove the most severely affected leaves. For stronger plants, consider cutting infected branches back to the trunk to prevent the spread of the infestation.
- Make sure to properly dispose of the infected branches. Burn or isolate the diseased branches in a sealed bag. If you're not careful, mealybugs could re-infest the plant.
Prepare for Multiple Treatments. Mealybugs go through four life stages: egg, nymph, pupa, and adult. Each method typically targets specific stages in the mealybug's life cycle. Therefore, if you're using a method to kill adult mealybugs, you'll need to continue treatment until all the eggs hatch into adults. You must be quick and patient to ensure newly emerged adults do not lay more eggs.
- Only the nymph and adult stages are truly harmful to the host plant. However, younger mealybugs will still develop into more harmful stages if not addressed.
- To determine the best treatment schedule, you'll need to understand the lifespan and developmental stages of the specific mealybug species. There are many species of mealybugs – including Silverleaf, Fig, Greenhouse, and Bandedwing – each with different lifespans.
Wash Plants with Soap Solution. Add a small amount of dish soap to 1 liter of water and mix it well. Pay special attention to the underside of the leaves, where most mealybugs congregate. Keep in mind that this method only targets adult mealybugs. Wash the plants every 3-4 days to remove newly hatched mealybugs. Depending on the mealybug species, you may need to continue treatment for several weeks until the infestation is gone.
- If using a stronger soap solution, wash the plants at the end of the day to avoid leaf burn.
Use Natural Predators. Many insects in nature feed on mealybugs, and you may be able to control the infestation by introducing the right predator species into your garden. The predator species you choose will depend on the type of mealybug. Consider using lacewing larvae, ladybugs, predatory beetles, big-eyed bugs, wasps, or assassin bugs.
- Be cautious when introducing foreign insects into your garden. While predators can help manage mealybug infestations, you might soon find yourself dealing with even more pests! Be sure to do thorough research before proceeding.
Using Traps
Using Yellow Sticky Paper. You can purchase these traps at garden stores or make them at home. Here's how: apply a slow-drying adhesive to a flat, yellow surface (cardboard or wood). Glue, honey, motor oil, or Vaseline are good options. It's believed that mealybugs are attracted to the color yellow. When the bugs approach the trap, they land on it and get stuck in the adhesive.
- If you're making your own traps, you may need to reapply the adhesive once it dries. For instance, glue can dry in a few minutes or hours. Motor oil or Vaseline might not work as quickly, but they tend to maintain their stickiness for a longer period.
- Remember to remove the traps if you're using a plant washing method or introducing natural predators to catch the mealybugs.
Place Traps Near Plant Leaves. Mealybugs typically gather on the undersides of plant leaves, so placing your traps close to their natural habitat will increase the likelihood of capturing these pests.
Know When to Remove the Traps. You can dispose of the traps when most of the mealybugs have died, and you're only catching a few bugs per day. These traps can also kill natural predators of mealybugs, so they're not suitable for dealing with low-level infestations, unless the predators can't control the bugs. If the mealybug population rebounds, consider setting the traps again.
Repelling Mealybugs
Repelling Mealybugs with Symbiotic Plants. Plants like marigolds and French or Mexican tarragon are known to repel mealybugs. You can plant these species in your garden to help prevent pest infestations! However, it's important to note that this is a preventive measure, not an effective solution if mealybugs have already infested your plants.
- Marigolds and tarragon planted in pots aren't effective at repelling mealybugs. Be sure to use the correct type of plant! If you're uncertain, visit a nursery and inquire about symbiotic plants that can help repel mealybugs.
Spray a mixture of water and soap on the plants. Mix rubbing alcohol with water in a 2:5 ratio in a 1-liter spray bottle, then add a tablespoon of dish soap. Spray a light layer of the solution onto the leaves of plants at risk of mealybug infestation. If applied carefully, this mixture should not harm most plants while helping to prevent the mealybugs from reproducing.
- Consider using natural oils, such as neem oil.
Apply worm castings at the base of the plants. It is believed that adding worm castings to the fertilizer of mealybug-infested plants can repel the pests for a few weeks or even months. Furthermore, worm castings are a nutrient-rich fertilizer that can stimulate plant growth. You can purchase worm castings from garden stores.
Cover the soil with reflective materials. Lay down a layer of aluminum foil or reflective plastic sheeting around plants susceptible to mealybug infestation. This will make it harder for adult mealybugs to locate the host plant, reducing the chances of them laying eggs.
- This step requires caution when watering your plants. Plants covered with plastic sheeting should be watered using a drip irrigation system.
- Do not use this covering in hot weather as it can cause the plants to overheat.
Use Chemicals
Understand the risks and benefits of using pesticides. On one hand, commercial pesticides can be an effective way to quickly eliminate pests. On the other hand, mealybugs are known for their resistance to chemical products. Moreover, these chemicals are often harmful to other organisms in the ecosystem, including plants, beneficial insects in the garden, pets, and wildlife in the area, and can even be dangerous for your family. Pesticides should only be used as a last resort.
It is important to note that whiteflies can quickly develop resistance to pesticides. In fact, their eggs and larvae are resistant to most common insecticides. If chemicals are used, it is crucial to rotate the pesticides every few days to prevent the whiteflies from adapting. Even with this strategy, there's still a high chance that the whiteflies will evolve resistance. You might inadvertently create a super-resistant strain of whiteflies that is extremely difficult to control!
Warning
- Repeated treatments are recommended to maintain effectiveness.
- While insecticides can be effective, they are also toxic if ingested. Many pesticides used to control whiteflies have been linked to fatal cases and a significant decline in honeybee populations, which are vital for pollinating flowering plants.
