It's hard not to like a ladybug. The round, brightly colored beetles don't look scary and are good guys in the garden, with both adults and larvae eating insect pests that harm your plants. Worldwide, there are more than 5,000 species of ladybugs that can be orange, red, black, yellow or brown and with varying numbers of spots on their wing covers. The ones you are likely to see are red or orange, without spots or with up to 12 spots.
1. Biological Control
The major advantage of ladybugs in the garden is to have a base population that can respond to harmful insects moving in. Ladybugs are predators of whiteflies, aphids, mites, mealybugs and scale insects, all pests with sucking mouth parts that feed on plants, stunting or killing the plants. Ladybugs can control pests without using insecticides. You may have to wait a while until the ladybugs reach effective numbers. Using natural enemies for pest control rather than chemicals is called biological control.
2. Attracting Ladybugs
There are specialist species of ladybugs, each eating a different kind of plant pest, so encourage a range of ladybugs to visit. Ladybugs supplement their predatory diet with pollen and nectar, so adding plants with abundant nectar attracts ladybugs. U.S. Department of Agriculture scientists found that ladybugs were healthier and more numerous when they had nectar plus prey to eat. Ladybugs often seek nectar from glands located outside of flowers such as on plants of stone fruit trees (Prunus spp.), morning glory (Ipomoea spp.) and passionflowers (Passiflora spp.), and in flowers such as dill (Anethum graveolens). Including these plants diversifies your garden and helps prevent large infestations of pest species. Prunus spp. generally grow in U.S. Department of Agriculture plant hardiness zones 3 through 9, and passionflowers generally grow USDA zones 5 through 11.
3. Life Cycle
Because larval ladybugs don't look anything like adult ladybugs, you need know what they look like so you don't kill them accidentally. Little spiny black larvae hatch from orange eggs and go through four stages before they are ready to pupate. Older larvae often have orange or white spots. They vaguely resemble tiny alligators and have an appetite to match. One ladybug may eat about 5,000 aphids during its life. The fourth larval form changes into a pupa, and the adult emerges about seven to 10 days later. This is an example of what's known as complete insect metamorphosis, and ladybugs are a handy way for children to learn about this process.
4. Learning Tools
Watching ladybugs in action teaches about predator-prey relationships. Encourage children to create a food chain or food web including ladybugs as a primary predator. Finding secondary predators that eat ladybugs might prove a problem, because the bright red color is a warning to potential ladybug predators that the beetles taste bad. The bodies of larvae and adults contain bitter-tasting compounds. A roughly handled ladybug oozes drops of unpleasant-smelling repellant orange fluid. Ladybugs encourage children to be interested in insects rather than to fear them. If small children handle ladybugs, monitor the interaction. Sometimes a ladybug can pinch the skin with its sharp little mandibles -- not enough to break the skin, but enough to be felt. The ladybug most apt to bite is the nonnative multicolored Asian ladybug (Harmonia axyridis).
- Encyclopedia of Insects; Vincent H. Resh, Ring T. Carde
- University of Wisconsin-Madison Department of Entomology: Know Your Friends: Lady Beetles
- Los Angeles Natural History Museum: Identifying Ladybugs
- University of Florida Department of Entomology & Nematology: Featured Creatures: Ladybirds, Lady Beetles, Ladybugs [of Florida]
- Cornell University College of Agriculture and Life Sciences: Department of Entomology: Biological Control
- Science Daily: Ladybugs Diet Influences Effectiveness as Biocontrol Agent
- University of Kentucky College of Agriculture: Entomology Department: Ladybugs
- Michigan State University Diagnostic Services: Multicolored Asian Ladybeetle (Harmonia Axyridis)
- Food Webs; Susan Heinrichs Gray
- John Foxx/Stockbyte/Getty Images