Whether you’re a keen outdoor gardener or an avid houseplant collector, if your plants have ever suffered a mealy bug infestation you’ll know all about the damage these fluffy little pests can do. And you’ll probably also know how hard it is to kill mealy bugs.
What are Mealy Bugs?
Members of the Psuedococcidae family of scale insects, mealy bugs are about an eighth of an inch long and have a white powdery appearance.
Mealy bugs feed on plant sap and generally position themselves under leaves and at stem joints, while they attack the plant with piercing mouths known as stylets. This penetrative feeding style damages the plant by draining its sap and transmits bacterial and fungal infections. Heavy infestations can kill a plant.
A Protective Layer
Mealy bugs are soft-bodied creatures, but they secrete a powdery wax layer over themselves. This protective layer gives them their name, as it makes them look as though they’ve been coated in meal or flour. It is also what makes it so difficult to kill mealy bugs.
Spotting a Mealy Bug Infestation
To spot a mealy bug infestation check stem joints, under leaves and other protected areas of the plant for what look like small balls of cotton wool. A plant suffering a significant mealy bug infestation will look wilted and may exhibit yellowing or deformed leaves. Due to the secretions the insects use to attach themselves to plants, foliage of an infested plant may feel sticky.
Given their waxy protective coating, their adhesive secretions and their persistent nature it can be difficult to kill mealy bugs. With patience, though, and your own measure of persistence, the task can be accomplished successfully.
A number of methods of killing mealy bugs are listed below.
Killing Mealy Bugs
The first rule of successfully ridding plants of mealy bugs is to catch them early. It’s far easier to kill one or two bugs than to eradicate a full-blown infestation. Inspecting your plants regularly is essential for early detection.
The Water Cure
One of the first attempts you can make to kill mealy bugs, and one that works well in the early stages of infestation, is to simply blast the bugs off with a strong stream of water. To be effective this treatment should be repeated on a daily basis until the mealy bugs are gone.
For larger infestations, try spraying with a mixture of dishwashing liquid and water. Use equal parts of each and stir to mix rather than shaking to avoid excess foam. Spray all infected areas. The soap coats the mealy bugs and effectively suffocates them. It also breaks down their protective waxy layer.
You can rub the leaves with a soft cloth after spraying to remove the bugs, or leave the solution overnight and then attack the weakened bugs with a strong jet of water.
Spot treat areas of mealy bug infestation with a cotton ball soaked in rubbing alcohol – simply dab the critters and rub them away.
Made from a mix of mild detergent and pyrethroids, insecticidal soaps are applied to the plant, its pot, and the immediate surrounding area. Insecticidal soaps are generally safe to use on greenhouse vegetables (but always check the label).
You can also mix insecticidal soap and horticultural oil together as an alternative approach to killing mealy bugs – use 1 teaspoon soap, ½ teaspoon horticultural oil and 1 litre of water and apply with a spray bottle.
Certain insects prey on mealy bugs and can help control infestations or prevent them taking hold in the first place.
Insects which kill mealy bugs include lady birds, lacewings and hover flies. Wasps will also kill mealy bugs and you can attract these to your garden (though it maybe a bit of a double-edged sword) by planting dill, coreopsis, fennel and bright flowers close to plants that my be targeted by mealy bugs.
There is also a commercially available mealy bug predator known as “mealy bug destroyer” (cryptolaemus montrouzieri) which can be purchased from garden shops.
Perseverance Pays Off
Beating these insects can be a bit of a drawn out affair, but with our tips on how to kill mealy bugs and a little perseverance you’ll be able to get rid of those fluffy white pests.
To learn more about killing mealy bugs check out this video.