Black aphids are not a pleasant sight on hibiscus plants, but they are not difficult to get rid of. The tiny sucking insects feed on nutrients inside leaves, robbing hibiscus of the nutrients it needs to produce healthy growth. Black aphids also spread disease by crawling over plants, potentially creating even more damage. With regular maintenance, gardeners can keep black aphids off their hibiscus flowers and keep the plants healthy.
Examine the undersides of leaves for aphids; this is where the insects feed and lay eggs. You will see signs of aphid damage on the top of leaves. As they move, aphids leaves behind a clear trail of shiny, sticky fluid.
Spray the plant vigorously with a garden hose when aphids are present.
Prune away all leaves that show signs of heavy aphid damage. The sticky goo they leave behind could attract disease even after the aphids themselves have gone.
Plant yarrow (Achillea), tansy (Tanacetum), Alyssum, spearmint (Mentha spicata) and caraway (Carum carvi) near hibiscus plants. The plants are natural pest repellents that keep aphids away.
Add a few drops of liquid dish soap to a spray bottle full of water and spray the solution on hibiscus leaves. The soap will kill existing aphids and their eggs.