Aphidoletes—Eating Their Way Through Aphid Colonies
The aphidoletes are small fly-like midges, two-winged mosquito-like flies that lack biting mouthparts. They appear in dancing swarms, especially near water. They're only active at night.
The larvae, which are maggot-like and approximately 1/10 of an inch (3 mm) long when fully grown, are the ones most often seen.
The midges search out 60 species of aphid colonies by their scent.
When they find a colony, they lay their eggs alongside it.
The tiny orange larvae appear in 2 to 3 days and feed on aphids, killing more than they can eat if aphid populations are high.
Adults eat the aphid honeydew and are active at dusk and during the night. Throughout the day they relax, hanging in webs in dark corners. Females will produce up to 100 eggs in their lifespan, which is about 7 days.
Buying Aphidoletes
These beneficial insects can be bought, usually through the internet, and shipped to you. They're normally used when a heavy infestation of aphids occurs, or in infested greenhouses.
They're usually shipped as pupae in vermiculite. Once the temperature reaches approximately 68-77 degrees F (20 to 25 degrees C), they can be released to the plants or trees where needed.
The recommended release rate is every 7 to 10 days, 2-3 times until established. For fruit trees in orchards, use 5,000-10,000 for 1-4 acres, two applications, 2 weeks apart. Commercial growers use them, normally in a blend with Aphidius, to check aphids in greenhouses.
Photo courtesy of
Whitney Cranshaw,
Colorado State University,
Bugwood.org
In commercialized rose operations, a heavy water spray or insecticidal soap spray prior to insertion of aphidoletes is suggested if aphid populations are high and damage is obvious.
Aphidoletes for greenhouse use come in blister packs that are hung on the infested plants. The adults appear, mate and lay their eggs near the aphids. The eggs hatch and the larvae begin to feed on the aphids. Every larva will consume up to 100 aphids before developing.
The adult is highly effective in seeking out aphids and only lays eggs on affected plants. The number of eggs laid is contingent on on the number of aphids, that is, more aphids bring more eggs. Using these beneficial insects is most efficient when there are aphid colonies on at least two plants.
Keep in mind that biological controls are living organisms that can be affected by the use of chemicals. If you've used any lasting pesticides in the recent past, check with the company you want to buy from prior to ordering Aphidius (a small parasitic wasp) or Aphidoletes.
Stop using pyrethrum 4 days before, rotenone 1 to 2 weeks before and soft soap insecticides 1 day before putting out Aphidius or Aphidoletes.
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