Asian Lady Beetles
Facts, Identification & Control
Harmonia axyridis (Pallas)
Multicolored Asian lady beetles are common throughout most of the United States and parts of Canada. The scientific name is Harmonia axyridis (Pallas). This is one of a very large family of beetles known as Coccinellidae. Many people call these beetles “ladybugs.”
Multicolored Asian lady beetles are about 7 mm long. As the name indicates, they occur in a wide spectrum of colors ranging from yellow to orange to red and have a varying number of spots. The variability of appearance in the adults can mislead people to think they are different species. A characteristic that assists in their identification is an “M” shaped marked located behind the head.
Behavior, Diet & Habits
There are many species of Coccinellidae in the U.S. and Canada. Most are beneficial insects. Plant specialists imported several species of lady beetles into the United States to control crop pests. The adults and larvae of most lady beetles are predators of aphids, mealybugs and scale insects.
In the fall, multicolored Asian lady beetles gather in large numbers on the outside of light-colored houses. As they gather on the house, some find cracks or holes. They use these holes to get inside. Some lady beetles enter quiet places like the attic. They hibernate through the winter and become active again in spring.
There are about 5,000 species of ladybug beetles worldwide, so depending on the species and habitat, there is a large variation in this insect’s lifecycle. For example, some lady beetles are predators, while others are plant feeders. However, all ladybug beetles undergo complete metamorphosis – four distinct life stages – the egg, larval, pupal and adult. The duration of the ladybug beetle’s lifecycle from egg to adult varies, but ranges from about 1-2 months.
A female ladybug beetle lays eggs in clusters on the underside of a plant leaf or twig. Generally, the female will choose a plant that is infested with their prey – aphids or scales. Eggs are laid during the spring and early summer. One fertile ladybug beetle can produce up to 1,000 eggs, and eggs hatch in about five days.
Larvae have been described as looking like very tiny alligators. If predators, the larvae feed upon their prey insects and may often consume some of the un-hatched eggs if prey is scarce. The larvae go through four instars, molting and becoming larger at each instar stage. The larval stage takes about 1-2 weeks to complete.
This is the insect’s resting stage when it goes through the transformation into an adult. Depending on the species and the environmental conditions, the pupal stage lasts about 3-12 days
Newly emerged adults feed on the same prey as the larvae and remain active until the weather turns cold when they seek protected overwintering sites. Depending on the species and location, ladybug beetles produce from one to several generations per year.
Eggs are deposited by females on the underside of plant leaves. The larvae emerge and will search for insects on the plant to prey upon. They eventually will pupate into adults. The time from egg to adult varies with environment and resource availability but typically is 15 to 25 days.
Signs of an Asian Lady Beetle Infestation
The most troubling sign of the multicolored Asian lady beetles is the mass appearance of large numbers of adults on and around buildings. This occurs during the fall with renewed activity on warm winter days and again in the spring. The larvae may be seen on plants or outdoor surfaces but, due to their radically different appearance from the adults, may not be recognized. More on lady bug infestations.
Control Lady Bugs
How to get rid of ladybugs when they’re indoors
Ladybug beetles are a problem for homeowners when they move inside our homes and other structures seeking a protected site to overwinter and then when they decide to once again move outdoors as the weather warms in the spring. When this happens, the following proactive and control actions are useful:
- Proactive Measures – keeping them outside
- Seal gaps and cracks where ladybug beetles may enter the structure. Pay close attention to areas such as siding, doors, windows, chimneys, ridge, soffit and gable vents and openings around pipes, conduit and utility wires
- Repair or replace damaged window or door screens
- Control Measures – getting rid of those inside
- The first thing to do when dealing with ladybug beetles is to contact your pest management professional and request an inspection. Your pest management professional will correctly identify the pest insect(s) and provide a plan for dealing with the problem.
- Some other effective and safe methods to deal with ladybug beetles are:
- Use a HEPA filter vacuum. Be sure to empty the vacuum bag after using it.
- Use a broom, sweep the insects into a dustpan or other container and put them outdoors
- Use insect light traps in locations that stay relatively dark and attractive to ladybug beetles such as attics.
- If the above methods do not work to your satisfaction, your pest management professional may apply the proper insecticides at the right time of the year to control ladybug beetles before they get inside your home.
How to get rid of ladybugs when they’re outdoors
During the summer, homeowners can prevent many lady beetle problems. Inspect the outside of the house carefully. Caulk cracks around windows and doors. Check the attic, roof and overhang vents. Repair any damaged screens. Check the weather stripping on all exterior doors. Repair any damaged window screens. Inside the home, patch any holes that lead into the attic.
Insecticide application on the outside of the home will act as a barrier. It will repel many of the pests that gather on the home and keep them from entering. The application should begin in the late summer. Because of temperature and other factors, the barrier will need to be re-applied periodically. The pest control professional has the equipment to make this treatment.
Are ladybugs harmful to plants?
It depends on the ladybug beetle species. Some species are predacious on other insects, which benefits plants, and others are plant feeders that typically damage agricultural crop plants. Identifying plant feeding ladybug beetles is simplified if a specimen is collected in the process of feeding and the person who identifies the insect knows what kind of plant the beetle was feeding on when it was captured.
Are ladybugs beetles?
Ladybugs are true beetles in the beetle family Coccinellidae. While they are commonly called ladybugs or ladybirds, pest management professionals generally prefer to call them ladybug beetles or ladybird beetles.