Begonia Pests

Begonias are grown and appreciated for their lovely flowers. There are several varieties of Begonias, and most are hardy in zones 9 through 11, although they are often grown as annuals in colder climates. Pests like mealybugs, spider mites, thrips, and snails are the most likely culprits that harm begonias. Fortunately, all of these bugs are treatable and preventable to different degrees. Learn how to spot the signs of an infestation and treat begonias to control bugs and limit their damage.

Common Begonia Pests

Mealybugs

Mealybugs are a form of sapsucker that harms plants like begonias by damaging the foliage and feeding on the nutrients intended to support the plant. The plant essentially starves to death as the bugs feed on the sap. These pests are a type of unarmored scale with a white, fluffy appearance. A minor mealybug infestation can damage foliage and stunt growth, but a major infestation can kill a begonia plant.

Treating Mealybugs on Begonia

Early detection is the best treatment for a mealybug infestation of begonias. Isolate a potted plant at the first sign of infestation to prevent the spread to other plants. Spray the plant with a hose to knock the bugs from the plant. Follow up by spraying the plant with a diluted solution of rubbing alcohol or an insecticidal soap. Multiple generations of pests can live on a plant at once, so it may take several rounds of treatment to effectively eliminate all of the eggs, larvae, and adult mealybugs on a begonia plant. 

Preventing Mealybugs on Begonia

Healthy plants are less likely to fall victim to mealybugs. Plants that are overwatered or overfertilized are more susceptible to mealybugs. Routinely spray the plant with water to knock pests loose, and preventatively spray begonias with insecticidal soap if you have had trouble with mealybugs in the past.  

Spider Mites

Spider mites are tiny sapsucking pests that feed on begonias. Signs of spider mite damage include tiny white or yellow dots, known as stippling. Delicate webs may appear between leaves or the juncture where leaves attach to the stems. Damaged leaves will eventually turn yellow and fall off the begonia plant. A heavy spider mite infestation will kill a begonia.

Treating Spider Mites on Begonia

Treat spider mites by cleaning the plant to remove webs and trim away damaged foliage. Spray the begonia with insecticidal soap or horticultural oil to treat spider mites. Several applications may be necessary if rainfall rinses the treatments away or multiple generations of pests are present on the plant.

Preventing Spider Mites on Begonia

Spider mites are more likely to infest a dehydrated plant. Do not overwater a plant, but keep a begonia appropriately watered to reduce the risk of spider mites. Spray the plants with water to remove dust and knock bugs off. Consider spraying the plant with horticultural oil as a preventative measure if you have previously struggled with spider mites.

Thrips

Thrips are tiny, winged insects that can damage plants like begonias. Infested plants will wither or have brown or silver streaks on the foliage. Leaves may appear pitted. New growth is more susceptible to thrip damage.

Photo by Adam

Treating Thrips on Begonia

Treat thrips on begonias by pruning damaged growth and spraying the plant with water to dislodge bugs. Spray the plant with insecticidal soap to further treat thrips. Continue to spray the plant weekly, or after rain or heavy dew, to fully eradicate these pests.

Preventing Thrips on Begonia

Prevent thrips by pruning dead or damaged growth and remove debris from around the plant. Provide proper care because compromised plants are more likely to become infected. Avoid over-fertilizing because new, tender growth is more appealing to thrips. 

Slugs

Slugs are gastropod mollusks that feed on foliage. Irregular-shaped holes on foliage and slime trails are signs of slug damage. These pests often measure a couple of inches long and may be visible. Slugs are more likely to hide under foliage, and they emerge in the evening, after it rains, or when a thick layer of dew coats plants. Slugs prefer cool temperatures and damp conditions.

Treating Slugs on Begonia

Treat a begonia damaged by slugs by removing foliage with heavy damage. Inspect the plant and remove slugs as you find them. Look under leaves and try to search in the evening or early morning when they are more likely to be active. Place a saucer with beer on the soil. The beer draws slugs in, and they drown when they wade into the liquid. Sprinkle a commercial slug bait like Sluggo on the soil, which poisons the slugs and adds iron and phosphate to the soil.

Preventing Slugs on Begonia

Slug prevention has a lot in common with treatment. Remove debris and dead plant matter so these pests have no place to hide. Routinely inspect the plant to identify the first signs of damage and be prepared to follow up with treatment as needed.

Begonia Pests Chart

Sources: 

"Begonia." Clemson University Cooperative Extension Service. hgic.clemson.edu

"Pests & Diseases in Begonias." American Begonia Society. begonias.org

Author Alison Cotsonas - Published 01-09-2024