Asian Lady Beetles in the House: How to Identify Them and Keep Them Out

One ladybug in the garden is a friend: it eats aphids. Dozens or hundreds of ladybugs on your windows in October are another story. They are almost always Asian lady beetles, an introduced species that has learned to spend the winter in our homes.

How to identify an Asian lady beetle

• Its colour ranges from orange-yellow to red, with a very variable number of black spots (sometimes none).
• It is a little larger than our native ladybugs, about 6 to 8 mm.
• The best clue: behind the head, a white area with a black M- or W-shaped mark.

Why they invade homes in the fall

As the cold approaches, Asian lady beetles gather on light-coloured, sunny surfaces, often south- or west-facing walls. They then slip through cracks, window frames, screens and soffits to spend the winter inside walls and attics. They leave behind a scent that attracts more beetles, which is why the same house is hit year after year.

What problems do they cause?

They do not damage the structure and do not breed indoors in winter. However:

• when disturbed, they release a foul-smelling yellow fluid that can stain walls, curtains and light fabrics;
• they can give a mild pinch, harmless in the vast majority of cases;
• in some people, large numbers of beetles can trigger allergy-like reactions.

Removing them without a mess

• Use a vacuum. Tip: slip a nylon stocking into the hose, held with a rubber band, to collect them and release or discard them outside.
• Avoid crushing them, so they do not stain surfaces.
• Light traps sold in hardware stores can help in an attic, but they do not fix the cause.

The real fix: block entry points before they gather

As with other fall invaders, prevention happens in late summer:

• caulk around windows, doors and outdoor electrical boxes;
• repair screens and add door sweeps;
• cover attic and soffit vents with fine mesh;
• check siding joints and where wires and pipes enter the house.

In homes that are hit every year, a professional exterior perimeter treatment applied just before the gathering period clearly reduces how many beetles make it inside.

Need help?

If ladybugs come back in large numbers every fall, our technicians can find the entry points and schedule the right treatment at the right time. Not sure they are Asian lady beetles? Check our Identify a pest page or call us at (514) 295-7696.