Gardening: Ladybird beetles, garden helpers
by Mary Robson, Area Horticulture Agent, WSU Extension
Chants and rhymes and hundreds of illustrations have made the red and black ladybug--or ladybird beetle--among the most recognizable of garden insects in temperate and tropical climates worldwide.
Knowing that these insects are beneficial seems to be embedded in human DNA. When their name was adopted for the VW "Beetle," several generations of drivers joined the circle of affection. In Germany, replicas of ladybugs are used as Christmas tree decorations for luck: This makes sense if future bad luck might include aphid, mite, or scale invasions.
Being cute is definitely an asset for an insect. The familiar oval silhouette telegraphs "good guy" at observers. Over 4,000 species have been described, nearly 500 of them in North America. In the maritime Northwest ladybird beetles occur in many patterns and colors, from unspotted solid black through pale orange with a few dark spots to deep maroon with many spots, and variations of the familiar red and black combination. It's not necessary to identify the genus and species to benefit from their presence--but many in this area are convergent ladybird beetles (Hippodamia convergens). Many others aren't.
In all colors, this beetle retains its resemblance to a child's toy, but it doesn't toy around in the appetite department. The nickname "Ladybug" comes from an obscure (untraceable) incident when the beetles attacked insects threatening grapevines, and grateful observers dubbed them representatives of "Our Lady, the Virgin Mary." Similar relief can flood over anyone staring at an Italian plum tree with leaves coated in aphids, when the realization strikes that it's also covered with adult ladybird beetles, pupa cases, and the stretched-out alligator-shaped larval stage. Help is at hand.
Learning to recognize the larval stage is the most important skill for gardeners who wish to protect and encourage lady beetles. The larvae are roughly carrot-shaped, spotted or banded in orange and black. Not knowing their value, people have gathered and mailed bottles of them to WSU for diagnosis, with the comment, "These are all over the trees, help me get rid of them!" Eggs are yellow, standing upright on leaves and branches in clusters of five to 50. They hatch in three to five days, and come out hungry. Larvae eat 300-400 aphids before pupating. The pupa case looks remarkably like the adult beetle in shape, but is grayish. Adults emerge in about a week. Their behavior when confronted with a good crop of aphid or mite prey reminds word lovers that the English word "beetle" derives from the Old English "bityl," meaning "biting."
Adult ladybird beetles overwinter in hibernation sites, under leaves or against warm rocks. During hibernation they survive on fat stored during summer. The beetles gather in huge numbers, particularly in some locations in California. Their hibernating habit has led to a cottage industry based on "bugging," gathering the lady beetles by the bucket for sale. Scooped up, packaged in mesh bags with a little sawdust, and refrigerated, the beetles are shipped to retail stores and hung on pegs. This practice, ostensibly intended to transfer beneficial insects into gardens, is the sort of act that makes ladybird beetle lovers want to say "drat" or worse.
Lady beetles often die during capture, in storage, or when released. If gathered in fall and stored, they will fly before eating and consequently leave the garden where they've been unpacked. It would probably bring good karma to buy and release packaged lady beetles, but it won't necessarily result in acquiring a good garden predator. Spraying stored packages lightly with sugar water can help improve the chances of survival, and letting them out at the base of shrubs in the cool of the evening can perhaps reduce their tendency to fly immediately.
An odd consequence of the industry that captures lady beetles for garden and agricultural use has been the recent reports of beetles gathering on or entering houses in late fall. Some species are accustomed to hibernating on warm limestone cliffs; they apparently take the southwest sides of white houses to be the same. Others enter houses and collect on walls, windows, and curtains. A frantic person with ladybeetles all over a wall may not want to hear that this occurrence is a natural result of the widespread introduction of them as helpful insects. They should be swept up and stored in the refrigerator for spring release, but this doesn't always occur to someone waving a broom in one hand and a phone in the other.
Encourage lady beetles to stay on site by making sure of food sources. These are predators, and they must have prey to survive. If the garden lacks aphids, mites, or scales, they will starve or leave. It's possible to think of aphids (metaphorically) as a kind of plankton, since they provide sustenance for so many other creatures. Do not use broad-spectrum pesticides that kill many types of insects.
Visit WSU's Agriculture Site on the World-Wide Web at http://www.cahe.wsu.edu.