Why do ladybugs suddenly swarm homes?
Written by
Tina Carter
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Pest control for ladybugs becomes urgent as they swarm into houses during the autumn season. Ladybugs look for cracks in exterior walls or windows to invade for warmth. One Vermont residence reported finding 3,000 ladybugs in their attic. Although harmless, they stained surfaces and created allergies until removed.
Exclusion Tactics
- Seal gaps wider than 1/8 inch with silicone caulk
- Install 20-mesh screens on vents and soffits
- Apply weatherstripping to doors/windows by late summer
Behavioral Insights
- Swarms target south/west-facing walls for solar warmth
- Pheromones from 1 beetle attract 500+ others
- Indoor lighting confuses navigation at night
Repellent Solutions
- Spray citrus oil (10% solution) on exterior surfaces
- Use camphor blocks in dry, ventilated attics
- Plant mint around foundations as a living barrier
Proper timing is crucial in determining success or failure. Ensure you properly seal your home by early September, before your outside temperatures fall below 50°F (10°C). A cabin owner in Maine sealed the cabin itself in August and, subsequently to sealing, determined that invasive beetles had reduced by 95% when they chose to cluster on the trees outside the cabin, and not the cabin itself.
Repellents based on citrus oil will dissuade beetles for a limited time, but will not kill them. To formulate a repellent mix for exterior sprays, use 1 oz of orange oil per gallon of water. Reapplication after heavy rain is advised. A family in Michigan has shared that they no longer have an ongoing pest issue after treating their window frames and fascia boards with this product.
For live infestations, simply vacuum the beetles lightly and put them outside. Avoid crushing the beetles, as their yellow defensive fluids can stain walls and fabrics. An antique textile preservation project at a museum in Minnesota relocated over 1,200 beetles using this technique and had no beetle casualties.
Read the full article: Ladybugs Pest Control: Benefits and Risks
