Hosts or Prey
Adelgids, psyllids, scales, and especially aphids
Identification
Adult multicolored Asian lady beetles (also called ladybugs or ladybird beetles) are dome shaped (convex) on top, flat on the bottom, and rounded when viewed from above. The body is about 1/4 inch (6 mm) long and 1/5 inch (5 mm) wide. There are more than 100 forms with different spot markings and coloration. Common in California are yellowish orange to red individuals with no spots or 18 or 19 black spots of variable size on the wing covers. Deep orange with prominent spots is the most common form in California.
A distinctive white border around the edge of adults' prothorax commonly surrounds (outlines) a black M- or W-shaped marking. In individuals with more white on the prothorax, the black marking presents as four or five dark blotches.
Eggs are bright yellow, oblong, and about 1/16 inch (1.5 mm) long. Eggs are laid on the underside of leaves in clusters, commonly with about 20 eggs.
Larvae grow up to 1/3 inch (8 mm) long and resemble tiny alligators. The body is mostly black to dark bluish gray. They have prominent tubercles (raised bumps) and branched, fleshy spines that are black or orangish. Larvae have bright yellow-orange on the top of abdominal segments 1 to 5, coloration that's especially prominent on the fourth (last) instar.
Life Cycle
The multicolored Asian lady beetle develops through four life stages: egg, larva, pupa, and adult. An adult female during her lifetime will lay several dozen to several hundred eggs. Overwintering is as adults, which can occur in buildings or as aggregations on low-growing vegetation.
Egg to adult development time during the growing season requires about 3 to 6 weeks. There are up to 6 generations per year.
Habitat
Multicolored Asian lady beetle can be found in almost any type of vegetation that hosts its prey. It was introduced to control soft-bodied pests on fruit and nut trees. Since arriving in California in the 1990s, multicolored Asian lady beetle has become the most common lady beetle in many habitats. It has outcompeted and displaced certain native lady beetles that were more common prior to its arrival in the state.
An adult beetle can eat more than 100 aphids per day. Each larva can consume about 600 to 1,200 aphids during its development through 4 instars. Because adults can live more than 1 year, an individual can consume over 5,000 aphids or similar-sized pests during its larval and adult lifespan.
This voracious predator has improved biological control of soft-bodied pests in various crop, garden, and landscape situations. However, the multicolored Asian lady beetle is also an unwelcome pest when it enters buildings during fall seeking shelter overwinter. When disturbed adults can emit drops of their odorous, orange blood. Adults are attracted to ripening fruit and sometimes contaminate grape and wine juices with their bitter-tasting blood that contains alkaloids it uses as defensive chemicals.
Species
About 150 species of lady beetles occur in California. In some habitats the multicolored Asian lady beetle is the most common lady beetle.
More Information
- Bad Side of a Good Beetle: the North American Experience with Harmonia axyridis, Biocontrol
- Harmonia axyridis (Coleoptera: Coccinellidae) Multicolored Asian Lady Beetle, Cornell University
- Multicolored Asian Lady Beetle (PDF), Ohio State University
- The Multicolored Asian Lady Beetle, Harmonia axyridis: A Review of its Biology, Uses in Biological Control, and Non-target Impacts, Journal of Insect Science
- Lady Beetles (PDF), Colorado State University
- Natural Enemies Handbook, UC Integrated Pest Management Program
- Protecting Natural Enemies and Pollinators, UC Integrated Pest Management Program
- Species Harmonia axyridis - Asian Lady Beetle, BugGuide, Iowa State University
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Coccinellidae
