Soft Scale Insect Pest Solution: Metaphycus

Metaphycus Description

Metaphycus (Pronounced: METTA-FY-CUSS) helvolus is a small parasitic wasp about 2mm in length. The female is yellow in colour and parasitises the young stages of soft scale when they have settled on the plant. It is quite active, walking quickly over the leaf surface. Metaphycus is pictured parasitising a scale.

Parasite Life Cycle

The adult female lays up to 6 eggs a day into soft scales. Before laying an egg, she tests the scale with her ovipositor (egg laying tube).  In so doing she kills up to four times as many scales.

The larva develops inside the scale and eventually kills it. These parasitised scales appear darker and flatter than normal. The parasite pupates inside the scale body and the adult emerges by cutting a circular hole in the dead scale. Adults can live for up to 2 months if enough food is available. From egg to adult takes about 11 days at 30°C and 30 days at 20°C.

Metaphycus Usage

  • Metaphycus is only suitable for use in a greenhouse or conservatory.
  • Metaphycus requires a minimum temperature of 22°C (72°F) for at least a few hours each day. This limits use to late spring and summer or hot greenhouses and conservatories.
  • Metaphycus requires good levels of light.
  • Metaphycus cannot be stored and needs to be used immediately upon receipt.
  • Metaphycus is harmless to children, pets and wildlife.