Lady BeetlesFort Bend County Master Gardener Fall 2001 Lady beetles belong to the beetle family Coccinellidae, which means "little sphere". There are probably as many as 4,000 species found worldwide, with over 350 kinds found in North America. There are many species of lady beetles in Texas. The convergent lady beetle is one of the most common and easily recognized species. Lady beetles are recognized are beneficial insects because both the adults and larvae feed on aphids and other small insects. Ladybugs or lady beetles have been recognized by many cultures for their beneficial predatory behaviors. The above nursery rhyme is English, and is based upon the ancient practice of burning hop fields following harvest time to eliminate aphids. Any larval stages of ladybugs would also face the same fate; only the immobile pupae, attached by their molt skins may have developed to the winged adult stage to "fly away home". The Coccinellidae contains over 4,000 species; almost all of these species are predators and feed on many different kinds of soft-bodied insects such as aphids and scales). The common names used for these insect predators include lady beetle, lady bug, or ladybird beetle. Adults of these insect predators are some of the most widely recognized insects in the United States. Most species of lady beetles are among our most beneficial insects as they consume huge numbers of plant-feeding insects --- mostly aphids. This fact and their attractive appearance have contributed to the generally good opinion of them held by most people. For instance, the French call them les betes du bon Dieu - "creatures of the good God" and les vaches de la Vierge – "cows of the Virgin". The Germans call them Marienkafer or "Mary's beetles". Identification Lady beetle adults have a very characteristic convex, hemispherical to oval body shape. The head is covered by a hood called the pronotum. Most adults have an orange body (many with black spots) and black pronotum (top of 1st segment of thorax) with white lines. Immatures are blue or black with orange spots, tapering bodies, and are ¼ - ½ inch long. Convergent Lady Beetle The long-handled scientific name for the convergent lady beetle is Hippodamia convergens. Although you may not think it, there are both male and female lady beetles. The common name is a translation of the scientific name, referring to a pair of white convergent dashes on the prothorax, the round plate behind the head. If the namer had looked from the other way, it could have been calledHippodamia divergens! Convergent lady beetle is one of the best known and most common American lady beetles and is found from Southern Canada to South America. Lady beetles are important natural enemies of aphids, whiteflies, mealybugs, scales and mites. Adults and larvae feed primarily on aphids and are especially important in reducing greenbug infestations in wheat and sorgum in Texas. Convergent lady beetles, sevenspotted lady beetles, and harmonia lady beetles were observed in Texas wheat plots in Wichita County, with convergent lady beetles being the most numerous species. Convergent lady beetle eggs look like other lady beetle eggs. They are yellow, spindle shaped, and laid on end in masses. Development from egg to adult requires about six weeks at a temperature of 60-75 degrees F and about four weeks at a temperature of 75-86 degrees F. The eggs then hatch into dark and alligator-like exotic larvae with three pair of prominent legs. They grow from about 1 mm to 4-7 mm in length over a 10 to 30 day period. They are constantly feeding - primarily on aphids, and have been compared to teenagers: Enough said! These voracious teenagers eat hundred of aphids and other insects that cause plant damage. After feasting on aphids, they will form a pupal case attached to a leaf somewhere near the feeding frenzy. The pupal stage may last from three to twelve days, depending on the location and temperature. One or two generations occur each year, depending on the length of the season, before the adults enter winter hibernation, usually in a protected site. Development from egg to adult may take only two to three weeks, and adults live for weeks or months, depending on the location, availability of prey, and the time of the year. In the spring, the adults disperse in search of prey and suitable egg laying sites. This dispersal trait is especially strong in Hippodamia convergens. Protection Lady beetles have some interesting means of protection. Their orange, red, or black coloration warns birds that they would not make a tasty meal. Birds learn that insects that are red, black, or yellow usually sting or taste bad and will leave such insects alone. Lady beetles can't sting, but probably do taste bad. They will also "play dead" when in danger. Many predators will not eat an insect that doesn't move. Lady beetles produce a bad smelling odor, perhaps by way of a fluid from joint in the legs, which may help to protect them. While lady beetles are not an endangered species, it has been named the official state insect of Ohio. Purchasing Beetles With such a good reputation, lady beetles have become a commercial item and are sold as a biological pest control agent. While it is true these beetles and their larvae feed on harmful garden pests, there are some limitations as to their effectiveness as a control agent. To use shipped-in beetles in your backyard is not a very good practice. While initially an active insect feeder in the spring, the convergent lady beetle later enters a "quiescent" or resting stage in the summer, when little feeding occurs while the beetles use their stored reserves of body fat. During this time, beetles usually aggregate in large numbers and are easily collected for sale. Unfortunately, once released, beetles collected during the aggregation state tend to leave the release area entirely or resume aggregation. They provide little garden insect control. However, there is one other option. Some lady beetle suppliers sell beetles collected during the spring feeding phase, or ones environmentally preconditioned to remain near the release point. These insects are less likely to depart from the area of release. Gardeners should be sure their supplier is selling this type of lady beetle. Black Sheep in the Family With all the kind words heaped onto lady beetles, one caution. There is a "black sheep" in the beetle family. It is a similar, common species of beetle that is a pest, called the Mexican bean beetle. It is very easy to distinguish. Adults have a yellowish-orange body with eight black spots on each wing cover. The larvae are also very distinctive, with large forked spines across their backside. The Mexican bean beetle is a defoliator of soybeans and green beans. Attracting Lady Beetles To make your garden suitable and attractive to beneficial insects, such as the lady beetle, a welcoming environment must exist. Besides feeding on pest insect populations that fluctuate seasonally, lady beetles need a consistent food source, especially nectar and pollen, water, shelter, and habitat for overwintering. Grow pollen and vector flowers: the Compositae family is characterized by flower heads that are actually made up of many small flowers growing together. Many flowers are composed of rays around a disk-like center. Many well-known ornamental flowers including marigolds, dahlias, daisies, asters, cosmos, calendula, coreopsis, tansy, yarrow, dill, zinnia, and sunflowers are in this family. Flowering often lasts over a long period of time and there is usually more than one flower per plant. This provides a slow flow of nectar over a long period for the insects. Lady beetles, lacewings, parasitic wasps and some predaceous wasps are attracted to plants in this family. Soldier beetles, flower beetles, and some lady beetles will feed on pollen in addition to feeding on insects. Dandelions offer early spring pollen to some of these insect predators. Conclusion The lady beetle is a beneficial insect. Creating and sustaining an ornamental landscape that attract beneficial insects is a giant step in developing a balanced garden. The lady beetle is an asset to all gardeners. Bibliography
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