Asian Lady Beetle: What to Know

Medically Reviewed by Jabeen Begum, MD on January 13, 2023
Written by Venkat S.R.
5 min read

There are thousands of species of lady beetles worldwide, several of which are common in the U.S. While some are native to the North American continent, many others were brought to this region to control exploding pest populations. But over the years, some lady beetles, including the Asian beetle ladybug, have themselves become a cause for concern. 

This article answers common questions like “are Asian lady beetles dangerous?” and “what do Asian lady beetles eat?” and explains what to do in the event of an Asian lady beetle infestation.

The Asian lady beetle, or Harmonia axyridis, is a common ladybug that has been widely used in the U.S. to control the population and spread of other insects and plant pests, such as scale insects, aphids, and mites. But they can become a nuisance themselves, especially during fall and winter when their population may grow beyond control.

Asian lady beetles are usually multicolored and you’ll find them in a variety of colors, such as yellow, orange, red, and black (although black Asian lady beetles are rare). Their bodies are oval in shape, curved outward, and roughly one-third of an inch long. They have light brown legs.

A unique feature of the multicolored Asian lady is the distinct “M”- or “W”-shaped marking — depending on where you look at it from — in the area between the head and the thorax. Although the “M” marking is more prominent on some beetles than on others, it offers a surefire way to identify this insect. Asian lady beetles typically have around five black spots between the head and the thorax that join to form the “M” marking. They also have between zero and 22 black spots on the hardened forewings on their backs (called elytra).

The Asian lady beetle life cycle usually consists of four stages:

  • Egg. Eggs are generally yellow and oval-shaped. Adult lady beetles look for safe areas, such as the undersides of leaves, to lay eggs. Lady beetles lay eggs in clusters of 20 around colonies of aphids and other soft-bodied insects to provide the young ones with a ready food source once they hatch. Eggs hatch after an incubation period of three to five days.
  • Larva. Once the eggs hatch, the larval stage lasts for roughly 10 days, after which they enter the pupal stage. Larvae are usually black and orange and look like tiny alligators. They spend most of their time on the plants where they hatch with plenty of food around them to help them survive.
  • Pupa. The pupal stage of Asian lady beetles lasts for around five days. In this stage, the beetles are covered in a cocoon and can’t move.
  • Adult. The lifespan of an adult Asian lady beetle can be anywhere between a month and three years, but most adult beetles live for one to three months. Larval and adult Asian lady beetles can eat hundreds of aphids in a single day.

In their native regions of Eastern Asia, these beetles are tree-dwelling creatures. They're found in the forests and orchards of Japan and are a common sight in soybean fields. The U.S. Department of Agriculture released Asian lady beetles in several states in an attempt to control the population of agricultural pests. In the U.S., the beetles inhabit crops such as roses, corn, soybeans, and tobacco in many states, including Georgia, California, Washington, Pennsylvania, Connecticut, and Maryland.

Some studies indicate that these beetles tend to move toward illuminated places and are therefore more likely to inhabit the brighter, southwest sides of houses where the rays of the afternoon sun fall. The type or build quality of the house is not as big of a factor compared with the light that falls on the house.

Asian lady beetles are not dangerous to the people or pets in your house. There are rare reports of Asian lady beetle bites when they’re picked up by people with their bare hands, but the bites are not serious, don’t cause the spread of diseases, and can be avoided by wearing gloves. Just keep in mind that these bugs are very helpful for farmers and gardeners and don’t pose any major health threat.

But these beetles do have a genuine nuisance factor, especially when their infestations reach sizable numbers indoors. Their secretions could leave stains on your upholstery and furniture. That said, Asian lady beetles don’t breed, lay eggs, or feed indoors, and they don’t pose any structural threats to your home.

Preventing these bugs from entering your house is the best way to avoid infestations. If you start noticing Asian lady beetles in your home, which tends to happen in the colder months, these notes may help you avoid letting any others inside:

  • Asian lady beetles can enter spaces as small as one-eighth of an inch. Make sure there are no cracks or crevices around your house that the bugs can use to enter your home.
  • Most importantly, seal all cracks and spaces around doors, windows, and roof boards. Check skirtings and areas where different materials join, such as roofs. If you see any cracks in such areas, you can fill those using sealants like silicone, latex, or acrylic caulks. Repair or change cracked door and window screens.
  • Other areas that are typically entry points for Asian lady beetles include wire and utility pipes, such as those for TV, phone, and cable wires as well as water pipes.
  • Make sure to fix the thresholds for all doors that lead into your house from outside.

Although this may not completely prevent Asian lady bugs from entering your home, it should keep away most of them.

It’s not recommended to use insecticides to get rid of these ladybugs as they don’t pose a very big threat to you or your home. You’ll be better off focusing your efforts on preventing their entry into your home. There’s no need to panic if you see Asian lady beetles in your home. They’ll most likely go away on their own once the outdoor temperatures rise.