Asian lady beetles, also known as multicolored Asian lady beetles or Harmonia axyridis, may look cute, but they can be quite destructive and infest your home. Although these bugs can bite, Asian lady beetles are not generally harmful to humans or pets. They are, however, an invasive pest across North America.
Of the thousands of species of lady beetles in the world, several hundred can be found in the U.S. Some are native species, and some, such as the Asian lady beetle, were intentionally introduced to help control crop pests. Unfortunately the tables have turned and this introduced species itself has become a pest.
During the 1960s through the 1990s, the U.S. Department of Agriculture released large numbers of Asian lady beetle in an effort to manage aphids and scale insects on pecans and apples, among other crops. Though the releases took place in specific states across the country, the beetles’ have spread and their range now includes most of the U.S.
How to prevent Asian Lady Beetles from invading
These pests can enter houses and other structures through the smallest of openings, which makes keeping them out a difficult task. Winterizing the home, sealing all gaps or cracks, and repairing damaged screens helps to keep Asian lady beetles out of the home.
Habitat, Diet, and Life Cycle
Habitat
Asian lady beetles thrive throughout the country, in both rural and urban settings. As they eat pests that damage crops, gardens, farmlands, and ornamental plants are all preferred habitats.
Diet
These beetles feed on a variety of soft-bodied crop pests, including aphids.
Life Cycle
Lady beetles can live for over a year. During this time, they go through four distinct life stages. They are:
- Egg: Laid in spring, eggs hatch in about three to five days.
- Larvae: Larvae emerge and seek out pest insects to feed on.
- Pupae: There are four molts before lady beetles pupate.
- Adult: Within several days, adults leave the pupal case.
Why do I have Asian lady beetles?
Native to Asia, these beetles were released in the US decades ago as a form of natural pest control. However, they have now become a nuisance in Canada.
Asian lady beetles can live for more than a year and thrive in both rural and urban environments, attracted to soft-bodied crop and garden pests like aphids.
During the winter months, Asian lady beetles also invade homes to shelter from the cold, entering through tiny cracks and gaps.
Fast Facts About Asian Lady Beetles
Asian lady beetles were first introduced to the United States in 1916. These little creatures look like yellow or orange ladybugs, and if they seem to be showing up everywhere, it’s because they are.
This invasive species was brought in initially to help control other small pests. In fact, they did American farmers a considerable favor by nearly wiping out the soybean aphid population. More recently, entomologists began questioning Asian lady beetles‘ value as natural pest control agents since they can contaminate grapes and other soft fruits, causing them to have a foul taste or odor.
Where Do Asian Lady Beetles Live?
Native to Asia, these insects now inhabit most U.S. states and much of Canada. They naturally prefer living in open fields of corn, soybeans, roses, alfalfa, or tobacco. As summers wane and autumn chills set in, Asian lady beetles can start to infest homes and other buildings. They wait out the cold months by hibernating in these protected places—a process called overwintering.
These insects are naturally attracted to light/dark contrasts, so they choose buildings with dark shutters against light siding, for example. Once they find a suitable dwelling, Asian lady beetles typically make their homes in sheltered areas such as wall cavities and attics.
What Do Asian Lady Beetles Eat?
Like North American native ladybugs, Asian lady beetles prefer to eat soft-bodied insects— aphids, mites, and mealybugs—and their eggs. They will also eat any other insects small enough for them to handle, including ladybugs and other beneficial insects.
What Is the Life Cycle of an Asian Lady Beetle?
Part of the family of small bugs called Coccinellidae, Asian lady beetles lay their eggs in early spring. In about three to five days, the eggs hatch, and the new larvae begin searching for food. Larvae eat the same thing as adults.
The larvae will molt four times, becoming bigger with each molting cycle. After the final cycle, the insect—now in its pupa stage—will be a full-fledged adult. The development process from egg to adult requires about 15 to 25 days. As adults, Asian lady beetles usually live about 30 to 90 days, but they can hold on for up to three years.
What’s Wrong with Asian Lady Beetles?
Although they can weed out garden pests, Asian lady beetles can become a nuisance when they invade your home or garden in large numbers—which they will. Asian lady beetles congregate in protected indoor locations in the winter. So, where one lands, many others will likely follow.
If you disturb an Asian lady beetle—especially if you swat or squash it—it will emit a foul-smelling, yellowish fluid. This fluid, technically the insect’s blood, can permanently stain carpets, curtains, and walls. Thankfully, this annoying secretion is not poisonous to humans.
Asian lady beetles may also bite humans and cause allergic reactions in some people. Though these insects are generally passive and only bite when searching for moisture or food, allergic reactions include itchy nose and eyes, asthma, welts, and swelling.
Outdoors, Asian lady beetles will eat other helpful insects once the aphids are gone. In addition, these insects carry a microsporidian parasite that can kill native ladybugs. They can also damage crops if they are present in large quantities.
