Multicoloured Asian lady beetle (Harmonia axyridis)
Multicoloured Asian lady beetle (Harmonia axyridis)
Multicoloured Asian lady beetle – Characteristics & Life Cycle
Get to know Harmonia axyridis: its variable appearance, biology, and tips for either encouraging or effectively managing it in your garden.
Key Facts
- Size: 5.5–8.5 mm
- Coloration: Highly variable, from yellow to red, with 0–21 spots
- Active: March–October, overwintering as adults
- Diet: Primarily aphids; also pollen & nectar
- Distribution: Native to East Asia, now established worldwide
Basic Data - Scientific name: Harmonia axyridis
- Common name (German): Asiatischer Marienkäfer (Asian lady beetle)
- Family: Coccinellidae
- Pronotum: Usually black with a white margin and M/W-shaped marking
- Elytra: Great variation in color and number of spots
- Larvae: Dark with yellow side stripes and spiny projections
Table of Contents
- Introduction
- Appearance
- Identification Features
- Diet & Ecological Role
- Life Cycle & Reproduction
- Seasonal Behavior
- Habitat & Distribution
- Practical Tips
- FAQ
- Conclusion
Introduction
The Asian lady beetle, Harmonia axyridis, is one of the most well-known examples of a beneficial yet problematic invasive species. Native to East Asia, it was introduced to many countries in the 1980s as a biological control agent against aphids. Today, it is widespread across the globe – and classified as an invasive species, since it not only feeds on pests but also competes with native lady beetles.
Appearance
This beetle has a hemispherical body shape, measuring 5.5–8.5 mm in length. Its coloration is extremely variable: the elytra can range from pale yellow to deep red, with spot counts between zero and twenty-one.
- Pronotum: usually black with a white border, featuring a distinctive M- or W-shaped pattern.
- Head and legs: dark in color.
- Antennae: short and clubbed.
Identification Features
- Color forms: wide range, from spotless red to heavily spotted yellow variants.
- Pronotum: characteristic M- or W-shaped marking in the black-and-white pattern.
- Tarsi: five segments on each leg.
- Larvae: dark gray to black with yellow side stripes and spiny projections.
- Pupae: yellowish to orange-red, often attached to the undersides of leaves.
Diet & Ecological Role
Harmonia axyridis is a voracious aphid predator. Both larvae and adults hunt aphids, scale insects, and spider mites. When prey is scarce, they also feed on pollen and nectar.
Its role is twofold:
- Positive: reduces pest populations in agriculture.
- Negative: its invasive spread displaces native lady beetle species, which are less competitive.
Life Cycle & Reproduction
- Mating in spring: beetles gather at aphid colonies.
- Egg-laying: groups of 10–50 eggs are deposited on the undersides of leaves.
- Larval stages: four stages over 10–14 days, during which larvae hunt aphids intensively.
- Pupal stage: 5–7 days; pupae often remain attached to leaves.
- Adults: first beetles emerge in spring; multiple generations may occur per season.
Seasonal Behavior
Active from March to October, these beetles seek shelter in late summer, forming large overwintering clusters in building crevices, under bark, or in other cavities. During mild winters, some may remain active.
Habitat & Distribution
- Origin: East Asia.
- Introductions: since the 1980s in Europe, North and South America, Africa, and Australia.
- Current status: widespread and dominant in many regions.
Practical Tips
- Encouragement: in spring and summer, support populations when aphids are present.
- Control: in autumn, prevent large groups from overwintering indoors by sealing entry points and removing individuals carefully.
FAQ
1. Is the Asian lady beetle harmful to humans?
No, it is not poisonous and does not bite. However, it may occasionally cause mild allergic skin reactions.
2. How can I distinguish it from native species?
By its size (5.5–8.5 mm), its wide color variation, and the characteristic M/W marking on the pronotum.
3. How do I get rid of beetles indoors?
Gently trap them in a container and release them outside – chemical control is unnecessary.
4. Does it benefit garden ecology?
Yes, as a natural predator of aphids. However, it weakens native lady beetle populations.
5. When are support or control measures appropriate?
- Support: in spring and summer, when aphids appear.
- Control: in autumn, before beetles seek winter shelters indoors.
Conclusion
The Asian lady beetle is both beneficial and problematic. It consumes vast numbers of aphids and supports agriculture, but at the same time threatens native species diversity. By combining encouragement in the garden with gentle control in autumn, you can make use of its benefits while minimizing its downsides.
