Trichogrammatoidea cryptophlebiae are used inoculatively, that is, relatively small numbers of wasps are released per hectare per release - their numbers increasing within the crop as the moth egg pressure increases.
Releases of 1,000 wasps per hectare are made for 6 to 10 consecutive weeks starting from early November to late December depending on the location.
The aim of this strategy is to parasitise some of the early laid eggs which may be below the level picked up in a standard monitoring check. One egg in 500 nuts is enough for Trichogramma to get started. When eggs start showing up in monitoring checks some of these are likely to be parasitised and are able to increase very quickly when the egg pressure rises. In this way sprays are likely to be saved.
If you wait until moth eggs are showing up in numbers before starting releases then it may be several weeks before parasitism rates are high enough to consider not spraying.