Insects

• A number of insects can infest gardenias. Small moth-like whiteflies are powdery white in appearance and less than 1/16-inch long. Tiny insects called scale often look like a fungus or disease on the plant. Their legs are hard to see and they are seldom mobile. Aphids are about 1/8-inch long with pear-shaped bodies in green, yellow, pink or black. Thrips are fast-moving but smaller still, at less than 1/16-inch long. They are thin, dark and winged. You may need to get close to the plant with a magnifying glass to diagnose which bug is infesting the gardenia.
  
  

Beneficial Organisms

• Pests on the gardenias each have natural predators that exist in the garden or that can be introduced. Avoid killing them with insecticides. The "good" bugs include parasitic wasps, ladybugs and ladybug larvae and green lacewings in adult or larval stages. You can purchase ladybugs, lacewings and nematodes to fight bug infestations. Some bugs, such as thrips, may need a few of these predators to keep them in check.
  
  

Insecticidal Soap or Horticultural Oil

• Insecticidal soaps or horticultural oils can be useful in clearing a bug infestation from gardenias. Use these products only after you have tried beneficial organisms or cultural controls. Water the plants 24 hours before applying oils or soaps; don't use them if the temperature is above 90 degrees or in drought conditions, as they may harm the plant. When aphids are the problem, spray oil or soap directly on the insects. The products will suffocate scales when applied liberally. Spray oils and soaps on the entire plant so insect invaders cannot avoid contact with it.
  
  

Cultural Controls

• Cultural controls are methods you can use in the garden to manually reduce insects or their habitat. The simple solution for aphids is to blast them off the gardenia with water. Remove ants too, because they work to protect the aphids for mutual benefit. Scale can be scraped off and destroyed. Shake the gardenia to get the whiteflies moving, then catch them with a vacuum hose. Always keep the area around the gardenia free of rotted matter that can invite bugs. Keep water from standing near the base of the shrub.