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Program Basics
Release Aphytis melinus every other week from mid-February through October. Parasite releases are most
effective on or before the beginning of the flight of the male red scale (approximately 700-degree days
from the last peak.) This may differ by location. Degree day accumulation is a gauge used in
conjunction with the pheromone trap catches to help indicate timing of releases.
Early season releases are critical because they allow the Aphytis melinus to build populations throughout the
orchard. Frequent releases are also critical because it is difficult to predict when the 3rd instar
scale will be present for the Aphytis wasps to attack. The scale may be at different stages as the
generation’s progress through the year.
Release approximately 5,000/acre each time for up to a total of 100,000/acre. More or less can be released
depending on the situation.
Prior to releasing, a phyto toxicity test is recommended if pesticides have recently been used
(i.e., within the last year.) Different insecticides have different lengths of residue; therefore, the
release-starting period will change accordingly.
Release Instructions
You will receive the wasps in paper or plastic cups containing 50,000/cup. Cool wet newspaper and ice
packs will be provided to keep the Aphytis melinus from overheating.
Keep the cups cool by leaving the newspaper moist and in the shade of the tree until you release them.
Never place in direct sunlight,except for accelerating a release, or leave unattended in a vehicle.
Temperatures rise very quickly inside the sealed container if left in direct sunlight.
They should be released in the early morning within 24 hours of receipt, but after temperatures have
risen above 55° F, but below 90° F).
Walk the orchard and spread the Aphytis melinus throughout. A good guideline is to release on each tree,
every 4th or 6th row. Tap the cup to have uniform dispersal.
Keep a vigilant watch for CRS build up and release extra Aphytis melinus in areas with high populations of California
Red Scale.
Aphytis melinus Quick Facts
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Aphytis melinus is the primary parasitoid of the California Red Scale.
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Aphytis melinus will over winter in all stages (egg, larvae, pupae & adult.)
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Extreme temperatures affect the reproductive cycles, therefore, annual releases are recommended in the
San Joaquin Valley.
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The quick dispersal of Aphytis melinus depends on the wind and temperature with 80° – 85° being the preferred
range.
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An adult may live 26 days with a food source.
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Egg to adult (80° F, 50% relative humidity) takes 12 – 13 days from the time of egg laying to emergence.
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One Aphytis melinus may destroy by host feeding CRS as well as egg laying.
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The number of offspring averages 24 per female.
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Aphytis melinus may attack any stage for host feeding but prefers 3rd instar for laying its eggs.
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