First used as a biological control agent in the late 1800’s, both the adult and larval stages of this beneficial insect attack and feed on all stages of mealybugs. The mealybug destroyer (Cryptolaemus montrouzieri) is a small (1/5 inch long), redish-brown lady beetle with dark-brown wing covers. A voracious feeder, “crypts” as they are often called, will also eat aphids and soft scales making them ideal for use in greenhouses, interior plantscapes, orchards and ornamental gardens.
Adult female predators lay yellow eggs among the cottony egg sacks of mealybugs. Eggs hatch into larvae in about 5 days, depending upon temperature. The three larval stages last from 12-17 days during which time the larvae feed on eggs, young crawlers, and the sugary liquid excrement, often called honeydew produced by the pest. Pupation occurs on sheltered plant stems or on greenhouse structures. Adults emerge after 7-10 days and live approximately two months. There are usually 4 generations each year.
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While this predatory beetle thrives on high mealybug populations, they are best released in early spring when the first pests are observed. The mealybug destroyer is most active at 70°F or higher and should be released at a rate of 0.5 per sq. ft. of planted area or 2-5 beetles per infested plant. In orchards release 1,000-2,000 adult beetles per acre of mature fruit trees. Mealybug destroyers should be shaken out close to mealybug infestations at dawn or dusk when they are least active. Repeat as necessary, usually once or twice a year.
Often after release, the mealybug problem appears to be worsening before it improves. This is because C. montrouzieri larvae are covered in a white, woolly material and are very similar in appearance to their prey.
Note: Used by the citrus industry in California, this predatory insect is credited with the complete control of the citrus mealybug (see Ladybeetles as Biological Control Agents in Citrus – PDF).
Tip: Ants feed on the honeydew that sucking insects (aphids, mealybugs, thrips) produce and will vigorously protect these pests from their natural enemies. If possible, control ants prior to release.
• Learn more about mealybugs here.
• Midwest Biological Control News – University of Wisconsin, Madison
• Cryptolaemus montrouzieri – Cornell University
• Natural Enemies Gallery – University of California Statewide IPM Program
• Researchers Discover Sex Potion to Ensnare Mealybug Pests – USDA (ARS)