Hibiscuses are a group of stunning shrubs, which grow in U.S. Department of Agriculture plant hardiness zones 4 through 11 and produce large tropical blooms. Despite being low maintenance, several species of bugs -- such as aphids, mites, scales, mealybugs and whiteflies -- use hibiscus as a host plant, laying their eggs on the shrub. Some bugs -- such as whiteflies -- cover their eggs with a white waxy material, making them easier to see. Other egg sacks, however, are microscopic, making them invisible to the naked eye. Thankfully, you can kill egg sacks on the hibiscus whether you see them or not.
Check the hibiscus for eggs sacks. Many hibiscus plant pests lay their eggs on the underside of leaves, so thoroughly examine the top and underside of the foliage.
Wipe any egg sacks you find off the plant with damp paper towels, crushing the egg sacks between the paper towels.
Spray the hibiscus plant with a steady stream of water from a hose to knock off hidden eggs sacks and sap-sucking insects. Spray the undersides of leaves as well as the tops.
Mix 2 1/2 fluid ounces of horticultural oil with 1 gallon of water in a handheld sprayer. Not all egg sacks are visible with the naked eye, and horticultural oil will help kill these hard-to-see sacks without harming beneficial insects.
Spray the mixture on the hibiscus until the leaf surface, stems and undersides of leaves are thoroughly coated. Repeat the treatment with a fresh mixture at 7 to 14 day intervals as needed.