Mealybug Destroyer (Cryptolaemus)
The most comonly used natural enemy of mealybugs are Crypts which are in the ladybug group of beetles. They are predators of mealybugs.
Crypt eggs are laid among mealybug colonies and hatch in 5-6 days at 81 degrees F. The four larval stages have wolly appendages of wax and resemble mealybugs. True legs are barely visible under the larvae.
The larval stages feed on mealybugs and live for a total of 12 - 17 days. The last larval stage can be longer than 1.3 cm (1/2 inch). Crypts pupate in sheltered places on stems or on greenhouse structures. Adults emerge after 7-10 days and also feed on mealybugs. Adult Crypts are dark brown with orange heads and tails, and are about 4mm (1/6 inch) long. Adults mate, and within 5 days females will begin to lay eggs (a total of 400-500 eggs in thir 50-day lifetime.) The life cycle requires about 31 days at 81 degrees F and 45 days and 70 degrees F.
Adults and young larvae prefer to feed on mealybug eggs, but the older larvae will feed on any mealybug stage. The adults can fly and cover large areas to search for food. If food is scarce, crypts will fly off in search of other related insects such as aphids and soft scales. A single larva can consume 250 small mealybugs.
Apply 5 Crypts per infested plant or 2-5 Crypts per square yard. In orchards release 1,000 - 2,000 per acre for mature fruit trees. Crypts are most effective when mealybug populations are high. Repeated relaeases are advisable.
The mealybug destroyer, Cryptolaemus montrouzieri, is a small (1/5") black lady beetle with a tan front end and a voracious appetite for mealybugs and some soft scales. This beetle was imported into the United States in 1891 from Australia by one of the early biological control pioneers, Albert Koebele, to control citrus mealybug in California. Though this beetle initially devastated the citrus mealybug populations in citrus groves, it was unable to survive the winter, except in coastal areas. Consequently, techniques for mass rearing this beetle were developed for its release into groves during the warmer months. The mealybug destroyer can be used to reduce populations of citrus and long tailed mealybugs in interior-scapes and greenhouses. Both species of mealybugs feed on a wide variety of ornamental plants. This predator readily feeds on some soft scales including hemispherical scale and its relatives, but reproduction is substantially greater on mealybugs. Adult female beetles lay their eggs among the cottony egg sack of adult female mealybugs. Eggs hatch into larvae in about 5 days at 80F. These larvae, whose waxy covering makes them superficially resembles mealybugs, feed on mealybug eggs and young crawlers. It takes another 24 days for these beetles to go through three larval stages and a pupal stage before they become adults. After four days, adult beetles begin to lay up to 400 yellow eggs during their two month life span. When releasing these beetles in the winter be aware that cool temperatures will slow development and reproduction. When the temperature is below 50F these beetles remain alive but do not produce many offspring. Beetles take 29 days to go from egg to adult at 80F and take 47 days at 70F. In the summer beetles thrive at 90F, but fail to reproduce at extremely hot temperatures (104F). Like most lady beetles, the mealybug destroyer has a tendency to fly when you release them from the container. Release adult beetles near mealybug infestations and keep windows and vents closed on the day of release. Mealybug destroyers feed on both mealybugs and their sugary liquid excrement, commonly called honeydew. Recent studies show that adults and larvae will spend more time searching a leaf for mealybugs if it has honeydew than if honeydew is absent. In small greenhouse areas, where mealybugs can easily be found by predators, mealybug destroyers will not persist after the mealybug population has been devastated. Did you ever wonder how the ladybug got its common name? After all, ladybugs tend to be such merciless predators of many obnoxious garden pests, they certainly don’t act like any lady my mother encouraged me to emulate! Ladylike or not, though, most (but not all) members of the ladybug family tend to be a gardener’s true friend. Before going further, let us do some technical “house cleaning.” Although they’re commonly called ladybugs (as well as ladybirds and ladybird beetles), the term "bug" is most properly used for the group of insects that classified as the "true bugs" (Order: Hemiptera). Common examples of the “true bugs” in the order Hemiptera include leaf-footed bugs, stink bugs and boxelder bugs. Because “ladybugs” are a type of beetle (Order: Coleoptera), the term lady beetle is most correct and is actually recognized as the official common name by the Entomological Society of America. Regardless of what they are called, lady beetles are among the most familiar and best loved of the insects that commonly occur in the garden. Gardeners along the Upper Gulf Coast of Texas are fortunate to be hosts to a very common, but not well-known, member of the lady beetle family: the Mealybug Destroyer (Cryptolaemus montrouzieri). Mealybug destroyers LOVE to eat mealybugs, especially citrus mealybugs (Planococeus citri) who, in turn, dine on many greenhouse crops, such as coleus, begonia, amaryllis, cyclamen and dahlia. This harmful pest also enjoys citrus crops, hibiscus, apple, English ivy, gardenia, oleander, persimmons, society garlic and many others. As you can see, the citrus mealybug can do a lot of damage to a lot of different plants. The little fellows - and ladies - did the job quite well, except that they are cold-sensitive and need to be reintroduced in spring in areas subject to long periods of cold. There’s no need for reintroduction here, though, with our (usually) temperate winters. Mealybug Destroyers are effective predators of aphids and various soft scales. The adult stage is small, 3-4 mm long (3 mm is slightly less than ⅛ inch.). Adults tend to quickly move away when disturbed. An additional reason for the adult stage of the Mealybug Destroyer not being well-known is that they don’t have the flashy patterning or coloring that occur in many species. Adults are dark brown with a tan-to-orange head and posterior. The resemblance of the larval stage of this predator to its prey is another reason Mealybug Destroyers may be overlooked or misidentified. With their wooly appendages and cigar-shaped body that looks as if it has been rolled in flour, Mealybug Destroyer larvae look very much like the larval and adult stages of the citrus mealybug (a serious insect pest). The important difference is size: full grown Mealybug Destroyer larvae are at least twice as large as adult mealy bugs. Mealybug Destroyers are not content to attack their prey at just one stage of development. The adult female lays her eggs in the cottony egg sack of the mealybug. As soon as they hatch, the destroyers start snacking. Adults and young larvae prefer eggs, while older larvae will consume mealybugs at all stages. One Mealybug Destroyer larva devours up to 250 mealybug lavae. They will even feed on honeydew, the sticky sugary substance secretedrvae. by mealy bugs. When honeydew is excreted (mealybugs typically “reside” on the undersides of leaves), it lands on lower leaves or on the ground, becomes colonized by sooty mold and making infested plants look even worse. Like other lady beetles, the Mealybug Destroyer has proven its usefulness as an effective biological control agent. To this humble, overlooked warrior with multiple common names, I would offer this invitation to my garden anytime.