How to Identify and Control Mealybugs In Your Garden

There are hundreds of insect species known collectively as mealybugs, nearly 300 of which are found in North America. They are small, oval, juice-sucking insects, 1/10 to 1/4 inch in size, that secrete a powdery waxy substance as a protective coating. This coating has a white, cottony appearance, and mealybugs are easy to identify when they appear on the stems and leaves of the plant. Mealybugs are warm-weather insects, so in northern climates they are primarily a problem in houseplants and greenhouses, and are rarely seen outdoors. In warm climates, however, they can cause serious problems for the entire plant.

Mealybugs are related to scale insects. They cause damage by sucking the sap from their host plants, and like many pests, mealybugs tend to encourage new growth. Over time, their damage can cause leaves to turn yellow and eventually fall off the plant. They can also cause premature shedding of fruits, vegetables, and flower buds. When the infection is severe, their waxy excrement (also known as honeydew) promotes the development of black mold. Let’s learn how to control mealybugs right here.

What are mealybugs?

Mealybugs are insects of the Pseudococcididae family of approximately 275 species that live in the United States. They share their superfamily, balloon superfamily, with soft scales.

Pseudococcal species prefer to congregate in shaded areas between plant parts, such as B. crevices, in tight spaces between touching fruits and leaves, on stems close to the ground, and as root-eating species between roots and soil.

These insects feed on most ornamental species, including woody and herbaceous perennials, flowers, trees (especially citrus trees), grapes, orchids, succulents and cacti, and even some grasses.

They are widely used in greenhouses and indoors because they like warm, humid climates.

These insects suck plant sap directly from the phloem with their pierced sucking mouthparts, basically like sharp straws.

The phloem is part of the vascular system that transports the sugar-containing products of photosynthesis (photosynthesis) through plants.

As a result, they often gather on leaf veins and midribs, happily feeding on the plant’s hard-earned nutrients.

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Like aphids, they secrete a thick, sweet liquid called honeydew from their abdomens. Black soot mold grows on these excrement, making the plant look ugly. Learn how to deal with sooty mold here.

Monitor

Because they are small and prefer to hide in sheltered areas, some plant-sucking mealybugs are easy to miss. That is, until they fully take over.

Check all cracks and whorls of leaves and flowers regularly, looking for egg masses, buildups of nymphs or adults, or single creepy reptiles.
Use a handheld lens to differentiate between these bugs or other insect and fungal infestations.

Check all outdoor plants before bringing them indoors for the winter.

Preferred hosts include many of the soft succulents we love to decorate our homes, such as orchids and various cacti and succulents.

Certain outdoor ornamental and fruit plants are also frequently affected, such as hibiscus, citrus trees and grapes.
If you notice yellow or wilted leaves, check the roots for subterranean infestation by removing the pot and gently tapping the soil away from part of the roots when the roots are no longer visible.

How to Control Mealybugs In Your Garden

To treat mealybugs on indoor and outdoor ornamental plants, try the Yates Baythroid Advanced Garden Pest Insect Killer Ready to Use Spray. This is a contact spray, so make sure you have thorough contact with the pest for the product to be effective. For severe infestations, use Yates Nature’s Way Vegie & Herb Spray Concentrate. Mix and thoroughly spray all surfaces of plants in a sprayer, repeating every 5-7 days if necessary.

Organic Control Methods

These insects are notoriously difficult to control.

They hide in sheltered places, grow a waxy coating that protects them and repels chemicals, spreads easily to new plants as well as tools and pots, and can survive without feeding on biological material up to two weeks.

Fortunately, there are multiple homeowner options, including some efficient and hungry nature volunteers.

Using an integrated pest management (IPM) approach is your best option as it optimizes and protects the natural enemies of these pests while providing effective control.

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Here you can learn more about IPM and how to design a good program for your garden.

Biological control

There are many predators in the landscape that will happily make a meal with mealybugs. Outdoors and when introduced into greenhouses, these beneficial insects can keep populations at tolerable levels.

Ichneumon wasps, ladybugs, green and brown lacewings, spiders, tiny pirate bugs and predatory mosquito larvae can mount impressive attacks on Pseudococcidae species.

Mealybug Destroyer (Cryptolaemus montrouzieri) is a shiny, plump ladybug with a red-orange head and thorax, black elytra, and an appetite for Pseudococcus.

You can buy these predators from Arbico Organics and introduce them to your greenhouse!

Leptomastix dactylopii are small amber wasps that parasitize older nymphs or adults by laying eggs inside these pests. The resulting larvae eat the host’s body from the inside out, turning it into a tough yellow mummy.

L. dactylopii is particularly effective against citrus mealybugs and can be used by greenhouse growers.

P. longispinus is attacked by the long-tailed mealybug parasitoid Anagyrus fusciventris.

This little wasp not only parasitizes older stage pests, but adult wasps also bite and feed on younger stage pests.

These predators are available from Arbico Organics.

Cultural control

If the female decides to use short legs, they can’t fly, and they can’t move quickly, so the insects don’t disperse quickly on their own.

If they spread, it’s most likely the factory owner’s fault. (Or in my mother’s case, a well-meaning daughter with a cutting gift…)

So it makes sense that the best way to protect your baby plants is to double-check any new arrivals before bringing them home. Also check your tools and pots, especially under the rim and in the grooves.

Clean up debris and remove loose bark, as they make a good wintering spot.

Destroy severely infected plants.

Avoid unnecessary fertilization, as excess nitrogen can cause plants to overgrow, resulting in fragile, soft growth that is more susceptible to harmful insects.

It can also lead to increased production of mealybug eggs.

How to Identify and Control Mealybugs
How to Identify and Control Mealybugs

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Physical control

If you have the time and a keen eye, you can pick mealybugs from your plants to physically remove clusters or individuals, especially when running out of them.

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Alternatively, spray plants with a powerful water jet to remove oocysts, crawlers, and adults.

Organic Pesticides

If you don’t have predators in your greenhouse or home, you may need on-site treatment.

Use a cotton swab soaked in isopropyl alcohol to remove buildup and egg masses.
Sprays can be ineffective because their protected spots make them difficult to reach. Plus, eggs and adults are safe from most contact sprays thanks to the moisture-wicking wax coating.

Insecticidal soap is effective against those in the crawling stage due to its variety of applications and good coverage.

Find insecticidal soap products like Bonide Insecticide Soap at Arbico Organics or at Home Depot’s Garden Safe Insecticide Soap.

Use horticultural oils (such as Monterey products from Arbico Organics) or neem oil to reduce pest populations before introducing beneficial insect species (such as Cryptolaemus montrouzieri or lacewings).

Let these products dry on the plants and get to work before releasing the beneficial insects. Note that neem oil can be toxic to pollinators like bees, so use it early in the morning or late at night when there are no bees.

Chemical Pesticide Control

Pyrethroids, such as bifenthrin, available from Home Depot, kill mealybugs.

However, keep in mind that pyrethroids can harm beneficial insects, so check for predators before using and use with caution!

Systemic pesticides are more effective than contact pesticides because they pass through the plant itself and be absorbed by any plant-eating insects.

If you choose to use these products, be sure to follow all packaging instructions for safe use.

Commercial growers sometimes use neonicotinoids such as imidacloprid and dinotefuran to control outbreaks because they do not require multiple doses. And because it’s systemic, you can get to places on the plant that pesticides won’t reach.

One day, when I’m sure my mother has forgotten who introduced mealybugs to her plant collection, I’ll broach the subject of how she treats them. Have you ever dealt with a mealybug infection before that? Tell globaltimes-sl.org in the comments below where you think it came from and a strategy you’ve used successfully!