Common Bugs on Begonias

Snails and Slugs

• Snails and slugs make short work of tender begonia leaves and will eat the flowers if they get a chance. Look for snails and slugs daily, especially under the leaves, where they tend to hide from predators and bright sun. Pick off slugs and snails with gloved hands and drown them in a bucket of soapy water. Add 1 to 2 capfuls of dish soap to a 1-gallon bucket of water. If you see large holes on the leaves but no signs of the culprits, wait until dark and then hunt for slugs and snails with a flashlight.

Aphids and Whiteflies

• Aphids and whiteflies love tuberous begonias. Both are tiny sap-sucking insects that live and feed in colonies, usually on the underside of a leaf. Whiteflies are white, while aphids can be green, brown, black or pink. Start by washing off both aphids and whiteflies with a strong stream of water. If they return or show signs of multiplying, spray the infested areas of the leaves with a ready-mixed insecticidal soap spray. Make sure to saturate all the affected leaves. Repeat the treatment weekly until the infestation disappears. Note that while aphids usually respond well to chemical controls, whiteflies are more difficult to get rid of.

Mealybugs

• Mealybugs affect both tuberous and wax begonias. They are sap-sucking insects that live in colonies. Look for white fluffy build up on the stems and leaves. You can remove a mild mealybug infestation by rinsing them off with water. If they persist, saturate the insects and the affected leaves with insecticidal soap spray. Reapply once a week until mealybugs disappear.

Thrips

• When growing wax begonias, thrips can pose a problem. These tiny insects are difficult to see. Look for browning spots on the tips of begonia flowers. If you suspect thrips but aren't sure, place a clean white cloth under the plant and then shake the begonia to dislodge the insects. Thrips are tiny brownish insects, 1/20 inch long. Get a magnifying glass to help spot them. Spray thrips with water to wash them off. Persistent problems can be treated with ready-mixed insecticidal soap spray. Reapply weekly on affected begonia plants. Even with regular applications, thrips are difficult to treat.