Tiny Black Insect on Hibiscus Plant

Aphids

• Aphids are prolific pests that attack many ornamental, vegetable and fruit-producing plants, including all types of hibiscus. According to the University of Florida, melon aphids can have several different body colors, including green, black, yellow and brown. Aphids are relatively small insects, often measuring 1 to 2 millimeters long, but they are still visible without a magnifying lens or microscope. Aphids steal water and minerals from their host by sucking sap from the soft tissue of new shoots, buds and leaves. A large infestation can cause heavy discoloration of foliage, deformed growth and decreased vigor of the plant. They can also transmit deadly viruses and bacteria from an infected plant to a healthy hibiscus.

Scales

• Hibiscus are vulnerable to infestations of scale insects, including the lobate lac scale (Paratachardina lobata lobata). Scales may be confused with deformed growth or a fungal infection because they remain stationer on branches for long periods of time. They anchor themselves on a suitable host and feed on the plant's sap through the wood of the trunk, branches and stems. According to the University of Florida, the lobate lac scale has a dark red-brown body, but the sooty mold fungus growing on their exterior usually makes them look black instead. A hibiscus infested with scales will perform poorly and may loose shoots and stems -- severely infested plants may die without treatment.

Fungus Gnats

• Fungus gnats (Bradysia spp.) can also damage hibiscus plants, although they are not a serious pest of ornamental or fruit plants. They are small flies with a black body and transparent wings. According to the Colorado State University, fungus gnats can produce a generation in 30 days and their larvae, which burrow into the soil, feed on fungal growths and plant roots. Managing moisture levels in growing soil and preventing it from becoming saturated helps prevent infestations of fungus gnats near garden plants.

Hibiscus Sawfly

• The hibiscus sawfly (Atomacera decepta) is primarily a pest of hibiscus, but they can also infest hollyhock and mallow species. According to the Connecticut Agricultural Experiment Station, these small sawflies, which are less than 1/4 inch long, are related to bees and wasps. They are completely black except for a single orange marking. They lay their eggs on the leaves of their host, causing discoloration and death of infested tissues. The larval worms hatch after a short time and consume their host's leaves for several weeks, then they crawl to the ground to finish their development into adults. A large infestation can significantly defoliate a tree, marring its ornamental value and compromising its health.