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. In fact, the Mealybug Destroyer was imported to the United States from Australia to control citrus mealybug infestations in California groves in 1891.
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 mealybugs.
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 larvae. They will even feed on honeydew, the sticky sugary substance secreted by mealybugs. 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:
Beneficials in the Garden & Landscape is an Earth-KindTM program coordinated through Extension Horticulture at Texas A&M University. Earth-Kind uses research-proven techniques to provide maximum gardening and landscape enjoyment while preserving and protecting our environment.
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