Ladybugs are small, plentiful, and insect-eating bugs that can invade your home by the jarful during warm months. Fortunately these often-colorful insects are not poisonous to humans and only harmful to pets if they eat the ladybugs. They do not carry human diseases, but that doesn’t necessarily mean they don’t have harmful side effects to some people who are allergic to them.
This article will explain more about ladybugs, give you some tips on how to keep them from coming in your home, and what to do if they do.
While there are thousands of ladybug species, the most prevalent by far in North America is the Harmonia axyridis ladybug or lady beetle (in England, they’re called ladybirds). This ladybug was actually brought over (on purpose) from Asia in 1916 because they feed on crop-destroying pests, including aphids. This is why most lady bugs are called Asian ladybugs or Asian lady beetles.
Although ladybugs maintained a rather peaceful existence with humans, in 1988, their populations became more overrun. As a result, ladybugs may be part colorful visitor, part pest.
Are ladybugs poisonous to people?
According to an article in the journal Allergy and Asthma Proceedings, ladybugs do not carry known human diseases. This means even if one bites or pinches you, they shouldn’t spread disease. Their presence in your home also isn’t likely to cause additional diseases. The only problem is they can be an allergen.
While they may be annoying in large numbers at home, ladybugs aren’t likely to be poisonous.
Are they poisonous to pets or livestock?
Dogs have been known to eat ladybugs in the past and experience some side effects from doing so, according to the American Kennel Club. Some case reports have found the lymph (fluid) the bugs secrete when a dog crushes the ladybugs in its mouth can cause damage that may be similar to a chemical burn. They can also have a burning effect on the gastrointestinal tract.
While this is a rare occurrence, some of the signs that your dog may have eaten ladybugs include:
- behavioral changes
- not pooping (dogs can’t digest the hard shells from the ladybugs so they may experience impaction)
If you’re worried about ladybugs with your dog, call their veterinarian. It’s possible that cats may attempt to eat them too, but case reports on the side effects in cats aren’t available.
The colors of ladybugs depend upon the ladybug’s variety, diet, and the region where they live. Their colors may also serve as a warning to predators or camouflage to protect them. A research study published in the journal
The researchers tested their theory that the more colorful ladybugs are more poisonous as their coloring is a sort of advertisement to predators not to mess with the ladybugs. Here’s what they found:
- black: Black ladybugs with small red spots are called pine ladybirds. They are one of the more toxic ladybug species and can therefore cause allergic reactions.
- brown: Brown ladybugs are usually larch ladybugs. This ladybug type relies on camouflage to protect it from predators. They are the least toxic ladybug species.
- orange: Orange-tinted ladybugs (which are mostly Asian lady beetles) tend to have the most toxins in their bodies. Therefore, they may be the most allergenic to humans.
- red: Red ladybugs tend to be more predatory and able to defend themselves. Red is a deterrent to many larger predators, including birds. However, they are not as poisonous as orange ladybugs.
The “poison” in ladybugs secretes a musky, unpleasant smell when the ladybug is threatened, which is actually their blood. It can leave behind a yellowish-red fluid in your home after you crush a ladybug.
Researchers have identified that Asian ladybugs contain two proteins that can cause allergic reactions in people. These proteins are similar to those of the German cockroach. Some people may have breathing problems, a runny nose, and sneezing as a result of a ladybug’s presence.
Ladybugs can also bite or pinch people. While they do not inject venom, their bite can leave a mark.
Ladybugs are averse to cold weather. For this reason, they start to go indoors more during the fall and winter seasons. They will start to re-appear in warmer times in the spring and summer when they start to feed on other soft-bodied insects or food they can find in homes, such as fruit, grain, and pollen.
Elements of a home that ladybugs are attracted to include:
- wary, sunny areas
- light colors
- cracks in walls or attic spaces
You can prevent ladybugs from entering your home by:
- sealing external cracks and openings that ladybugs could potentially crawl through
- installing screens over roof vents and checking current window screens for signs of damage
- planting mums and lavender, known to naturally deter ladybugs
Ensuring ladybugs can’t get in your home in the cooler months can make for a more enjoyable (and ladybug-free) time during the warmer months.
Ladybugs release blood from their joints (what bug experts call reflexive bleeding) when threatened. This can create an unpleasant smell and release proteins that trigger allergies. For this reason, it’s best to avoid crushing ladybugs, especially if you are allergic.
Ways to treat ladybugs include:
- Spraying insecticides, such as deltamethrin, cyflhthrin, cypermethrin, or tralomethrin, outside the home. If you aren’t sure how to safely apply these, contact a pest professional.
- Putting up light traps inside your home. These traps attract ladybugs with a bright light. You can then empty ladybugs outside your home.
- Sweeping up dead ladybugs.
- Applying diatomaceous earth around windows and doors in your home. This soft sediment contains silica, which will cause ladybugs to dry out and die.
Some people use products with lemon that may act as a deterrent to ladybugs. However, these haven’t been definitively proven to kill ladybugs.
Ladybugs don’t carry diseases and are helpful to you if you have a garden, but they are not without other risks and nuisances if they infest your home. Through careful preventive and treatment measures, you can keep them at bay.