Asian Lady Beetles Identification Guide

Asian Lady Beetle Identification Guide

Physical Characteristics

Asian lady beetles are small, dome-shaped insects that look like native ladybugs. They are 5 to 8 millimeters long, about the size of a pencil eraser. The easiest way to spot them is by the M-shaped or W-shaped black marking on the white area behind their head. This area is called the pronotum. The marking can be thick or thin depending on the beetle.

These beetles come in many colors. Some are pale yellow or tan. Others are bright orange or deep red. The number of spots also varies a lot. Some have 19 or more black spots, others have just a few, and some have none at all. This makes them tricky to identify by color alone. The marking on the pronotum is the most reliable way to tell them apart from native ladybugs.

Common Species

Only one species of Asian lady beetle lives in North America:

• Multicolored Asian Lady Beetle (Harmonia axyridis): This species came from eastern Asia. It was brought to North America several times to help control crop pests. It has since spread across the continent. Its habit of gathering in large groups inside buildings during winter makes it a major nuisance pest.

Asian Lady Beetle Behavior and Biology

Asian lady beetles feed on aphids and other small insects. Both adults and larvae eat these pests. A single beetle can eat hundreds of aphids in its life. This made them useful for crop protection, which is why they were brought to North America.

In late summer and early fall, adult beetles start looking for shelter to spend the winter. They like light-colored surfaces that are warmed by the sun. South-facing and southwest-facing walls are very attractive to them. The beetles gather on these warm surfaces before finding their way inside through cracks and gaps.

Once inside, Asian lady beetles go dormant. They cluster in wall voids and other hidden spaces. On warm winter days, they may wake up and move into living areas. They are drawn by warmth and light. This can happen many times throughout winter and early spring.

Female beetles lay clusters of yellow eggs on plant leaves. The larvae are long and covered with small spines. They are black with orange markings and look very different from the adults. After feeding for several weeks, larvae turn into pupae and then emerge as adults. There can be several generations per year in warmer areas.

How We Treat for Asian Lady Beetles

The best way to control Asian lady beetles is to treat before they start looking for shelter in fall.

• Exterior Barrier Treatment: Before the weather turns cold, usually in October, we apply dust treatments in exterior voids. This includes weep holes, behind siding, and around windows and doors. The dust creates a barrier that keeps beetles out. We also treat the outside perimeter with a repellent to stop beetles from landing on your home.

• Entry Point Inspection: We check your home for gaps and cracks that let beetles in. Common entry points include gaps around windows and doors, torn screens, spaces where utility lines enter, and openings along the roofline. We tell you which spots to seal.

• Interior Treatment: If beetles are already inside, we treat the areas where they gather. Repellent materials around window seals, door frames, and baseboards help push out active beetles. In bad cases, we may need to treat wall voids where beetles cluster.

• Seasonal Timing: Fall treatment before the first hard frost is key for pests like Asian lady beetles. We time our work to protect your home when beetles are most active.

The best results come from combining treatments with sealing entry points. Blocking gaps keeps beetles out even after treatments wear off.

References

• Multicolored Asian Lady Beetle - Penn State Extension
• Asian Lady Beetle Infestation of Structures - University of Kentucky Entomology
• Multicolored Asian Lady Beetle - University of Minnesota Extension
• Harmonia axyridis - Global Invasive Species Database
• Asian Multicolored Lady Beetle - Kansas State University Extension