Scale

• Scale appear as small, brown discs that attach themselves to the underside of leaves, especially along the veins. They are immobile as adults and create a waxy outer shell that can protect them from sprays. Scale may be difficult to identify as often they look like part of the plant itself. Remove scale with a damp cloth or cotton ball. Treat plants immediately because scale secrete a sticky substance that encourages mold growth. Wiping the plants with warm soapy water can help control scale; treat acute infestations with a systemic insecticide.
  
  

Fungus Gnat

• As small black adult insects flying around the plant, fungus gnats are harmless. The problem occurs when these flies lay their eggs on the compost surrounding the plant. As the eggs hatch, small, black-headed maggots begin to feed on the organic matter in the compost and occasionally devour young roots. Avoid overwatering to reduce the risk of attack.
  
  

Thrips

• Thrips are a relatively minor pest. The tiny insects leave silvery streaks on leaves and can cause damage to flowers, leaving the blooms spotted and distorted. Hanging sticky yellow cards near an infected plant may help because thrips are attracted to the bright color and can be trapped in this way.