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Adults are tiny, 1.4 mm (1/15 inch) long, dark brown to black, hemispherical beetles; females have reddish yellow heads, lighter colored than males.
Larvae are elongated, cream colored, covered with short fine hairs and have conspicuous legs.
The adult beetles fly, while larvae are slow moving and travel from plant to plant on leaves.
Optimum conditions are moderate to high temperatures of 61-90 ºF (16-350ºC); Delphastus do not fly at temperatures below 55 ºF (13 ºC).
Delphastus do not enter diapause under short-day conditions, therefore remain active all season.
Three weeks after the first introduction, expect to see larvae and pupae on the underside of leaves.
After 4-5 weeks, the first beetles should be found feeding on whitefly eggs among the adult whiteflies.
Two months after the first introduction, all stages of Delphastus should be present in the oldest whitefly infested areas.
The complete life cycle takes 25-21 days at 78-86oF (25-30oC).
Eggs are yellowish ovals, laid on end, in clusters on the underside of leaves. Females lay 2-6 eggs per day, and can lay over 300 eggs in their life time. Females must eat 100-150 whitefly eggs per day to initiate and sustain egg laying.
Larvae feed for 7-10 days. Older larvae migrate down the plant to pupate. Pupae are often found clustered along leaf veins on the undersides of leaves.
Adults emerge from pupae in 6 days. Adults can eat 150-640 whitefly eggs or 11 large larvae per day. A single beetle can consume as many as 10,000 whitefly eggs or 700 larvae during its lifetime.
Both adults and larvae feed on whitefly eggs and immature stages. If food is scarce, they will also feed on other small arthropods, such as spider mite and aphids, and will cannibalise their own species.
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