Asian lady beetles, also known as Harmonia axyridis, were introduced to North America in the early 1900s as a form of biological pest control. While they do prey on pesky aphids and other plant-damaging insects, these non-native ladybugs have now become invasive pests themselves in many regions.
Unlike the cute and harmless native ladybug species, swarms of Asian lady beetles tend to invade homes each fall to overwinter, leaving behind yellowish stains and a strong, foul odor. Getting rid of large numbers of these unwelcome guests can be challenging, but there are several effective control methods you can try.
Understanding the Asian Lady Beetle
To get rid of Asian lady beetles effectively, it helps to understand some key facts about these insects:
Appearance and Size
- About 1/4 inch long; slightly larger than many native ladybugs
- Vary in color from pale yellow-orange to darker red-orange
- Distinctive black ‘M’ or ‘W’ shape on whitish forewings
Diet and Behavior
- Feed on plant-damaging aphids, scales, and mites
- Swarm on structures in fall seeking protected places to overwinter
- Give off a foul-smelling yellowish fluid when disturbed or crushed
Reproduction and Lifecycle
- Females lay clusters of eggs on plants in spring
- Larvae emerge and feed on other insects through summer
- Multiple generations occur each year
- Overwinter as adults emerging in spring to mate and lay eggs
Preventing Asian Lady Beetle Infestations
While Asian lady beetles can fly and crawl their way inside even well-sealed buildings, there are some prevention tips that can help reduce the number that get indoors:
Seal Potential Entry Points
- Caulk and seal gaps around windows, doors, rooflines, and openings for utilities
- Ensure door sweeps and weatherstripping provide a tight seal
- Screen vents, chimneys, and other openings they could enter through
Avoid Attracting Them Outdoors
- Remove food sources like aphid-infested plants or fallen fruit
- Fix exterior lights that are attracting night-flying Asian lady beetles
- Clear away leaf litter, grass clippings, and other organic matter
Monitor and Remove Them Promptly
- Inspect the outside of your home and look for aggregations of beetles
- Vacuum or remove them from surfaces before they can make their way inside
- Capture and release native ladybugs back outside
Killing Asian Lady Beetles Already Indoors
If Asian lady beetles have already made their way into your home, you have several options for killing and removing them:
Vacuum Them Up
- Use a vacuum cleaner with a hose attachment to suck them up
- Concentrate on windows, curtains, ceiling corners, and under furniture
- Empty the vacuum contents into a sealed bag and dispose of it
Crush Them
- You can crush individual beetles with a tissues or paper towels
- Just be prepared for the foul-smelling yellow fluid some will emit
- Flushing crushed beetles down the toilet is an effective disposal method
Insecticidal Sprays and Dusts
- Products with pyrethrins or pyrethroids will kill on contact
- Spray corners, windows, baseboards, and other aggregation spots
- Dusts can be applied into wall voids and other hidden spaces
Freeze or Heat Treat Infested Items
- Place smaller items in freezer bags and freeze for 4+ days to kill all stages
- Heating infested items on a high dryer or oven setting over 120°F also kills them
Diatomaceous Earth and Desiccant Dusts
- Spread these abrasive dusts in thin layers where beetles are crawling
- The fine particles abrade their exoskeleton causing dehydration and death
- Reapply after vacuuming up any dead beetles
Deterring Asian Lady Beetles from Entering Your Home
To further discourage Asian lady beetles from invading your living spaces, there are some extra deterrent steps you can take:
Install Exclusion Screening
- Fine mesh screening as small as 1/16 inch can help block entry points
- Pay special attention to vents, chimneys, weep holes, and openings around window AC units
Apply Repellents Around Entry Points
- Insect repellent strips containing DEET or natural oils can deter entry
- Reapply repellents periodically as they wear off
- Take care to keep them away from food surfaces or children’s areas
Use Indoor Lighting Selectively
- Turn off exterior lights at night during fall beetle swarming season
- Close blinds and curtains in the evenings to avoid light shining outside
- Use yellow bulbs which are less attractive to the beetles than white lights
Keep Up Air Circulation and Cool Temperatures
- Asian lady beetles prefer warmth and are drawn to heated buildings
- Running AC and fans keeps indoor spaces cooler to make them less attractive
- Keep garage and attic doors closed so warmth doesn’t attract them
Install Indoor Traps Near Entry Points
- Adhesive traps or pheromone traps can catch some beetles before they spread
- Be sure to check and replace traps frequently to remove accumulating beetles
Removing Asian Lady Beetle Stains and Odor
In addition to eliminating the live beetles, you’ll want to address any stains or foul odors they may leave behind:
Clean Stained Surfaces Promptly
- Remove yellowish stains as soon as possible before they set in
- Use a cloth dipped in rubbing alcohol or non-bleach cleaner
- For fabric stains, apply stain remover and wash in warm water
Eliminate Beetle Odor
- Wipe down surfaces where crushed ladybugs released odor
- Clean with an enzyme-based pet odor eliminator or hydrogen peroxide
- Place bowls of baking soda or activated charcoal to absorb lingering odors
Air Out the Area
- Open windows or set up fans to circulate fresh air through the space
- Running an air purifier can also help filter out unpleasant odors
- You may need to repeat airing out the area several times
Mask Remaining Odor
- If odor persists, set out fragrance bowls, sachets, or essential oil diffusers
- Citrus, eucalyptus, peppermint and other strong scents can override mild odors
- Avoid scent overload that could worsen the problem
Discouraging Asian Lady Beetles Long-Term
To reduce Asian lady beetle issues over the long run, focus on making your home and yard less attractive to them:
Manage Aphid Populations
- Asian lady beetles are attracted to plants with aphid pests
- Use ladybug-safe methods like horticultural oils or insecticidal soaps to control aphids
- Avoid over-fertilizing plants which can make them more susceptible to aphids
Eliminate Alternative Food Sources
- Pick up fallen tree fruits that could attract beetles
- Avoid planting trees or shrubs prone to sap leaks, aphids, and fungal growths
- Fix leaky faucets, pipes, or exterior leaks providing moisture lady beetles seek out
Modify Landscaping and Exterior Lighting
- Remove vegetation touching the home or overhanging the roofline
- Prune back shrubs and branches to eliminate hiding spots
- Switch to yellow bulbs for necessary exterior lighting to deter night swarms
Perform Exclusion Repairs in Early Fall
- Inspect your home in early autumn and seal any new entry points beetles could use
- Make sure screens are in good repair and install weatherstripping as needed
- Caulk, seal, and repair gaps before beetles start looking for overwintering spots
Work With Neighbors to Reduce Nearby Infestations
- Swarms can migrate back and forth between properties
- Share information on control methods and prevention tips
- Coordinate timing of exterior lighting changes and yard cleanup
Frequently Asked Questions About Controlling Asian Lady Beetles
How do I tell Asian lady beetles apart from beneficial native ladybugs?
Asian lady beetles tend to be slightly larger and more oval-shaped than many native species. They are variable in color but often have a distinct black ‘M’ or ‘W’ shape on their whitish forewings. They also give off a foul odor when disturbed or crushed.
Why do Asian lady beetles come into our homes in the fall?
Asian lady beetles are looking for protected places to spend the winter during their dormant season. They often aggregate on vertical surfaces like walls or windows on the sunny side of buildings. Warm buildings with accessible cracks and openings are ideal overwintering spots.
Are Asian lady beetles dangerous or harmful?
While not medically dangerous, Asian lady beetles can inflict irritating bites in some cases. The foul-smelling secretions they emit and the stains they leave behind are also quite bothersome. They do prey on pest insects outside, but become a nuisance when large numbers congregate indoors.
How can I keep Asian lady beetles off my windows and walls outside?
Apply insect repellent strips or spray products containing natural oils or chemicals like DEET around windows, doors, vents, and other entry points Asian lady beetles are attracted to. Reapply them regularly according to label directions to maintain effectiveness.
Does spraying pesticides outdoors help reduce beetles coming inside?
Spraying outside surfaces is generally not very effective since new beetles can quickly re-infest the area. Instead focus on exclusion, removing indoor entry points, and maintaining repellents around specific problem spots where beetles are attempting to enter the structure.
What temperature should I heat treat infested items at to kill Asian lady beetles?
Heating small household items like books, papers, stuffed animals, or linens at 120°F for 1 to 2 hours is sufficient to kill all life stages of Asian lady beetles. For proper control, maintain this minimum temperature throughout the item for the full duration.
How long after treatment will it take to get rid of Asian lady beetles indoors?
After implementing control measures like exclusion, vacuuming, spraying, and trapping, it usually takes 1 to 2 weeks to eliminate most indoor Asian lady beetles. Stragglers may continue appearing over the next few weeks as they emerge from hidden overwintering spots. Persistence is key to complete control.
Is it a good idea to seal my home up tightly in the fall to keep Asian lady beetles out?
While sealing and caulking entry points is recommended, you still need ventilation and air circulation within your home. A tightly sealed home can lead to issues with moisture, condensation, and indoor air quality. Focus on excluding pests while still allowing necessary airflow.
How can I stop beetles from swarming around my exterior lights at night?
Switching to yellow bulbs for your exterior lighting can help make them less attractive to night-flying Asian lady beetles. Also be sure fixtures are not emitting any ultraviolet light which attracts beetles. Direct lights away from the home and use motion sensors so lights are only on when needed.
Conclusion
Dealing with significant infestations of invasive Asian lady beetles in your home each autumn can be frustrating. Understanding their biology and behavior patterns better equips you to implement a more effective control program. An integrated pest management approach utilizing exclusion, traps, repellents, removals, and pesticide applications timed before beetles start moving in gives you the best chance of success. Paying close attention to reducing entry points and food sources around your home also discourages re-infestation year after year. With diligence and persistence, you can minimize the nuisance of seasonal battles against swarms of unwelcome Asian lady beetles in and around your home.
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