Aphid Pest Solution: Aphidius

Aphidius Description

Aphidius (Pronounced: AY-FID-EE-USS) is a small slender winged parasitic wasp about 2mm long and black in colour. The female lays single eggs into immature aphids (greenfly or blackfly).

A parasitised aphid appears swollen & “mummified”, ranging in colour from gold or bronze to brown or black.

Aphidius is widely used as aphid pest control in greenhouses by commercial growers.

Aphidius Life Cycle

One female Aphidius lays up to 100 eggs in her lifetime. Eggs are laid into immature aphids.

After the Aphidius egg hatches, the larva develops inside the growing aphid, eventually killing it. The parasitised aphid then takes on a mummified appearance.

The parasite fixes the dead aphid to the leaf with a silk thread. Then the Aphidius larva spins a cocoon inside the aphid, from which it finally emerges as an adult wasp. A circular emergence hole can be seen in the back of the aphid.

The complete life cycle takes about 3 weeks at 20ºC (68ºF).

Aphidius Usage

  • Aphidius is ideally introduced as soon as single aphids are seen on the plants. It works much better on small, isolated patches of aphids, rather than large colonies.
  • Once established, large aphid populations can be hard to get rid of.  Use SB Plant Invigorator organic spray, targeting colonies before introducing Aphidius (which can be released as soon as the SB treated leaves are dry).  In this way colonies are reduced, allowing Aphidius to operate more efficiently on any survivors.  However SB should NOT be used once the beneficials have been released
  • Aphidius is a strong flier. Ideally, vents and/or doors near plants being treated need to be closed or netted over to prevent Aphidius from escaping.
  • Aphidius is more efficient on some plants than others, and seems to prefer non-hairy leaves.
  • Aphidius is only recommended for use in a greenhouse or conservatory.  In the garden, naturally occurring Aphidius and other parasites and predators will usually appear spontaneously.  Spraying colonies with SB Plant invigorator  organic spray will often help this natural process.  Beware not to use toxic chemical pesticides in the same way.  The opposite effect may be achieved, as aphids become resistant and natural beneficials are killed.
  • A minimum temperature of 10ºC (50ºF) is required. At lower temperatures, use SB Plant invigorator to keep numbers down until Aphidius can be introduced.
  • A temperature of 18ºC (64ºF) is desirable for at least a couple of hours a day to allow the parasites to be at their most active.
  • Aphidius cannot be stored, it needs to be used on the day of receipt.
  • You will know when Aphidius is working as you will be able to see parasitised or “mummified” aphids on the leaves.
  • Aphidius is harmless to children, pets and wildlife.

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