While ladybugs are beneficial to species control outdoors, they can be a nuisance indoors. They can also bite you. While their bites aren’t known to be lethal or overly harmful, some people can experience allergic reactions to their mere presence.
Keep reading to find out how and why ladybugs may bite you, and what to do if you have a ladybug infestation in your home.
Although more than 5,000 ladybug species exist worldwide, there are 24 known species in the United States. Scientists specifically introduced some ladybug types into the insect population because they prey on other insects, such as aphids, which destroy crops.
While ladybugs have decorative red or multicolored patterns that are pleasing to look at, they can bite people. They can also “pinch” people using their legs. This can produce a bite or mark that may lead to a skin welt in people who are allergic to ladybugs.
In a 2004 study, an entomologist placed 641 beetles into 11 different plastic containers, washed and dried his hands, and then put his hand into the containers to see if the ladybugs would bite him.
He found that 26 percent of the 641 beetles bit him. The study concluded that they were more likely to bite areas that weren’t covered by hair, including the fingers and inside of the wrist. Once a beetle broke the skin, he found other beetles would come and feed on the area. The female ladybugs were slightly more likely to bite than male ladybugs.
The researcher wasn’t necessarily threatening the ladybugs, but they still bit him. This may mean that ladybugs may mistake human skin for fruit or other substances they may feed on.
Theoretically, because all ladybugs have a mandible or legs, they can bite or pinch you. In the United States, the most common beetle is the Harmonia axyridis (H. axyridis) beetle. Other species include:
- Asian lady beetle (orange ladybugs)
- ladybug beetles
- ladybird beetles or ladybirds
These ladybug types are the most common in the United States and therefore the most studied related to biting. They’re also the only ladybugs known to invade homes.
Some people are very allergic to ladybugs. The ladybugs have proteins present in their bodies that can cause breathing and swelling of the lips and airways (known as angioedema), according to the American Academy of Allergy, Asthma & Immunology (AAAAI).
Researchers have found similar proteins in the German cockroach, another insect that can cause allergic reactions.
Ladybugs tend to invade people’s homes in the fall and winter, seeking the warmth of your home. They’ll usually hibernate until early spring.
Ways to prevent ladybugs from entering your home include:
- Ensure all doors and windows are properly sealed. Even small gaps less than 1/16 of an inch can allow ladybugs to enter. Get door sweeps, thresholds, or weather stripping to ensure ladybugs can’t enter through doorways. Use a high-quality silicone or acrylic latex caulk to seal gaps in windows.
- Check for alternate entry points, such as openings where pipes, wires, meters, and television cables enter your home. You can seal these (or keep bugs out) using caulk, expandable foams, steel wool, or copper mesh.
- Plant flowers known to naturally repel ladybugs, like mums and lavender. You can also keep these plants in your home.
Getting rid of a ladybug infestation in your home requires attention to treatment and prevention.
Use insecticide sprays on the outside of your home. The best time to spray is usually late September to early October, before ladybugs try to make their entry for the winter. Examples of sprays include permethrin, deltamethrin, and lambda-cyhalothrin. Professional pest companies can also offer these services and ensure you get even coverage.
Vacuum and sweep up ladybugs in your home to help remove them. Just be careful if you choose to handle them by hand — ladybugs defend themselves by bleeding from their joints. Doctors call this reflex bleeding. As a result, if they’re roughly handled, their blood can stain upholstery, carpets, and walls.
Create homemade ladybug traps by cutting off the top of a 2-liter plastic soda bottle 6 inches from the top, placing jam or jelly in the bottom of the bottle, and inverting the top so the bottle’s mouth is pointing downward. Ladybugs can enter the trap, but they can’t leave it.
Apply diatomaceous earth to key areas of your home. This is a soft sediment that contains silica, a natural pesticide. Place it around areas where your walls meet the floor. Ladybugs stuck in the diatomaceous earth will dry out and die.
Once the ladybugs die, it’s important to make sure you remove them from your home. Otherwise, they can continue to cause allergic reactions.