These parasitic wasps have long been recognised as effective natural enemies of armoured scale insects. Aphytis are tiny yellow wasps (two or three adults can fit onto a pinhead) capable of short flights. There are 3 principal species of Aphytis: africanus, lingnanensis and melinus. The species bred by Du Roi IPM is Aphytis lingnanensis.
In the case of Aphytis lingnanensis, the adult female wasp lays her eggs under the scale cover and onto the body of a third instar, unmated, female scale. In field conditions the adult female will live for about 2 weeks and will lay approximately 50 eggs during her lifetime. Once the egg hatches, the Aphytis larva feeds on the body of the scale insect, eventually killing it. The following generation of Aphytis reaches maturity about 2 weeks after egg laying and is ready to mate and continue the cycle. Adult wasps also use scales as a source of food. This feeding will injure the scale, resulting in death. For every generation of Red Scale, Aphytis will experience about three generations - they cycle three times faster than Red Scale.
Aphytis parasites favour well foliaged, healthy trees providing shelter from extreme heat and low humidity. Dust is harmful to most beneficial insects and mites and makes effective pest management in these areas (next to roadways) difficult. Wetting of roads will assist in minimising the dust hazard.

How to Make Use of Aphytis Augmentative Releases
Aphytis should be released before scale insects have reached damaging levels. If no releases are conducted, natural Aphytis populations will probably develop but the time taken to reach effective population levels required for commercial control is often too long. This leads to higher scale populations at harvest reducing fruit quality and yield.
The ideal time to begin augmentative releases of Aphytis wasps is in spring and early summer after the initial thripicide sprays have been applied and before scale insects have built up to damaging levels. Release rates should be highest shortly before and during the period that the male scale flights take place. Male flights are determined using pheromone traps. Winter releases can also be effective but at much lower release rates. Due to the low temperatures experienced during the winter months, scale breed slowly and there are fewer scales present in suitable instars (3rd) that can be parasitised. Booster releases should be made if very high summer temperatures are experienced or scale are still at high levels late in the season. Do not release Aphytis too soon after applying toxic chemicals and avoid harsh chemical applications after releases (Please contact us at contact@duroibugs.co.za with any technical or related queries).
Aphytis are supplied in plastic tubs containing 10 000 wasps each. Open the lid and place the tub on a branch on the shaded side of the tree. The Aphytis will fly out of the tub and immediately begin to search for the scale insects. It is also possible to release Aphytis by opening the tub and driving slowly through the orchard in the shaded area of the tree rows. Distribute the consignment of Aphytis evenly throughout the orchard. The cooler box containing the Aphytis tubs should not be exposed to direct sunlight since excessive temperatures will result in high mortality of the wasps. Keep the cooler box in an air-conditioned room and release the parasites early morning or late evening. Because Aphytis wasps spend the majority of their life cycle developing within and feeding on the scale insect they are difficult to detect after release.

Release Rates Recommended: 150 000 wasps per hectare per season. If pheromone traps are not used to detect male Red Scale flights, then the parasites should be released in equal numbers every 2 weeks from November onwards. Further releases should be made where scale populations are high. To ensure that Aphytis have established, regular monitoring by an experienced scout is recommended after release. With experience the level of parasitism can be assessed. A microscope is required. Continue releases until at least 50% of available stages of scale have been parasitised, i.e., second, and unmated third instar female scale.