Aphids are two to three millimetres long, soft-bodied insects that feed on plant sap. They are translucent green or black in color. They are found on the underside of leaves and new shoots. Infested plants are wilted, with yellow, twisted and curled leaves that eventually fall off.
Growth is stunted and, in bad cases, new buds are poorly formed.
Pick off the adults you can see and spray thoroughly with water to remove the eggs. Safer's Insecticidal Soap at 20 millilitres per litre of water, or Pyrethrum 0.2 per cent according to label instructions, should give good control. Fungus gnats are three to six millimetre black flies. The adults are harmless but the young maggots live in the soil and feed on the roots and crown. They thrive in moist soil.