Brown and Black Bugs on a Ficus Tree Branch

Scale Insects

• Brown and black scale insects are sap-sucking insects. They establish themselves on a plant, and suck sap from the leaves or stems. At the larva and nymph stage, the insects crawl around on the ficus tree. Once they get established, scale insects cover themselves with a waxy coating produced by the insect body. The waxy coating provides protection for the feeding adults, and for the egg and larva stage of the developing young.

Affects

• A minor scale infestation rarely causes noticeable damage to a healthy ficus tree. However, a heavy infestation can weaken a ficus tree as the bugs deplete the tree of fluids and nutrients. An added problem is sooty mold. As scale insects feed, they leave behind a sticky residue. Fungus grows on the residue creating black spots, called sooty mold, on the affected ficus tree. Sooty mold doesn't harm the ficus, but it looks unsightly.

Manual Control

• You can control a mild scale infestation several manual ways, particularly on small potted or outdoor ficus trees. Pick off all the hard scale insects or gently remove them with a scrubber. Place potted trees in the tub or outside in mild weather, and wash the leaves and branches thoroughly. Make sure to remove the scale insects and the sticky, mold-forming residue they leave behind. Use a hose for small, outdoor landscape ficus trees. Dabbing individual insects with a cotton swab soaked in rubbing alcohol works to kill scale insects as well.

Chemical Control

• When manual control practices fail, chemicals can help control scale insects. The best time to treat a scale insect infestation on a ficus tree is when the insects are in the crawling stage. Once they get under the waxy covering, it's hard to reach them with chemical sprays. Spray the ficus tree with insecticidal soap or oil spray. Use chemical sprays with caution and follow the directions on the package label. Repeat the treatment every one to two weeks until the brown and black bugs are gone.