Pest Profile: Multi-colored Asian ladybird beetle


Ladybugs go by many names, although ladybug is the most common variant in the United States. They are also called lady beetles, ladybird beetles, and ladybirds.

Ladybugs do a lot of good by eating bugs that feed on plants. Left unchecked, aphids and other sap-sucking bugs can destroy and damage gardens, crops, and ornamental plants. The piercing mouthparts of plant-eating bugs causes leaf curling, yellowing, puckering, and stunting, while their sugar-laden droppings encourage the growth of mildew. Most ladybugs are voracious predators of damaging plant pests - a single ladybug can devour several thousand aphids within its relatively short lifetime.

There are many species of ladybugs, around 500 in the United States, and about 6,000 worldwide. While you might picture ladybugs as being red with black spots, many forms exist. Some are tiny and black, others are black with red spots, and others still are pale or spotless. The most common ladybug in our area is the multi-colored Asian ladybug. Although it eats pests, it is also a pest itself.

Asian ladybugs come in a stunning array of colors and patterns. They are usually red or orange with black spots, and the shield-like region directly behind the head has a black M-shaped marking on a white background. They can have no spots or they can be mostly black, but these patterns are not as common as the typical red with black spots that we associate with ladybugs.

As the name suggests, Asian ladybugs are not from around here. While our native ladybug species spend the winter in brush piles, behind the bark of trees, or in other natural shelters, Asian ladybugs have an unfortunate tendency to seek out light-colored structures in which to overwinter, or hibernate. Once inside, they plan to go dormant, but our houses are too warm and they cruise around, confused that it might be springtime already! If they like your house, and there’s a hole that they can get in through, expect to have at least a few ladybugs invading your home in the fall. If you’ve suffered with ladybugs before, you’ll likely suffer with them every year unless you can find out how they’re infiltrating your home.

Ladybugs are brightly colored because they taste bad. They have noxious compounds in their blood that make them distasteful to predators. If you’ve ever pestered an Asian ladybug and noticed it left a brown stain on your hands or on a surface, you might be surprised at what the liquid is. Ladybugs can cause themselves to bleed from their leg joints, a process called reflex bleeding, so they can get their nasty chemicals on their attacker. It saves them from having to be chewed on to demonstrate their bad taste. If a ladybug falls into your food, they can leave behind a taste that may ruin a portion of your meal.

I’ve never been bitten by a ladybug, but people do get bit. Ladybugs, being predators of other insects, have chewing mandibles capable of landing a solid pinch, but they are not aggressive towards humans. Biting is usually done in self-defense; they prefer to reflex bleed when disturbed.

If ladybugs are driving you crazy in the fall by assaulting your home, you have two options that should be used together: getting rid of them on the inside and preventing them from getting inside. You’ve likely already faced them this year. Large clusters in the house can be vacuumed up. Try to avoid touching them, as they can stain surfaces with their blood. Since they are inside, there must be a way that they got indoors. You need to look around for holes and gaps and seal them up. Inspect window screens for tears. Ensure that pet doors seal tightly. Check up high and down low – ladybugs readily fly and they are very determined.