Target Pest: Citrus mealybug (Planococcus citri) and other related mealybugs
Description: Cryptolaemus is the most commonly used biological control for mealybugs. Adult beetles are dark brown with orange heads and tails, and are 1/6 in. long. Larvae are alligator shaped, up to ½ in. long, and are covered with white waxy hairs that make them resemble mealybugs.
Use in Biological Control: Cryptolaemus is used to control mealybugs mainly in interior plantscapes. They can be used outdoors, but will not survive sub-freezing temperatures. They are less effective on longtailed mealybug (Pseudococcus longispinus) because this species lacks the cottony masses that Cryptolaemus requires for egg laying.
Optimum conditions are 82°F (28°C) with relative humidity of 70-80%, but can be used in a temperature range of 61-91°F. Below 48°F, they are completely inactive and above 91°F they stop searching for prey. They are most active in sunlight, therefore are not as effective during dull winter months. For control of citrus mealybug, Cryptolaemus can be used along with the parasitic wasp Leptomastix dactylopii.
Life Cycle: The complete life cycle takes about 31 days at 81°F (27°C) and 45 days at 70°F (21°C). The sex ratio in the population is about equal, with somewhat fewer females than males (40% females). Eggs are laid among the cottony egg masses of mealybugs. They hatch in 5-6 days at 81°F. Females will lay 5-10 eggs per day, for a total of 400-500 eggs in their 50 day life time.
Larvae feed on mealybugs for 12-17 days, and then pupate in sheltered places on stems or on the greenhouse structures. A single larva can consume 250 small mealybugs. Adults will emerge in 7-10 days. They will then mate, and females begin laying eggs in about 5 days. Adults and young larvae prefer to eat mealybug eggs, but older larvae will feed on all stages of mealybugs. If food is scarce, they will also eat soft scales and aphids.
Release Rates: Cryptolaemus is most effective when mealybug populations are high. Repeated releases are advisable if mealybug populations are low. Because many foliage plants grow slowly, it may take 2-4 months before results of mealybug control programs are apparent. Un-infested new growth is a sign of control.
Interior Plantscapes/Greenhouses: 5 beetles per infested plant, or 2-5 beetles per square yard.
Outdoors: 1,250-12,500 beetles per hectare (500-5,000 per acre) near the mealybug infestation. First releases outdoors should be in early spring.
Orchards: 2,500-5,000 beetles per hectare (1,000-2,000 per acre) for mature fruit trees. Repeat as needed.