Asian Lady Beetle

Identification

Asian lady beetles are commonly seen in Madison, Wisconsin during the fall and have a smooth and oval body that is convex in shape. They may or may not be marked with spots, but all have a black “M” or “W” marking on their head. They can be seen in a range of colors, ranging from orange to yellow to red or even (rarely) black. This beetle typically has 19 black spots which can vary in appearance from well-defined to more than faint traces on its wing covers. They are up to 8 mm long, which is slightly larger than the native lady beetles.

Lifecycle

Asian lady beetles go through complete metamorphosis, which means they have four stages of development: egg, larva, pupa, and adult. The lifecycle from egg to adult takes 15-25 days depending on temperature and food availability.

Eggs: Females will emerge in spring and lay eggs on host plants, such as aphids-infested crops or trees. They do not lay their eggs in homes. The eggs are yellowish and oval-shaped and are laid in clusters of 10-50 on the underside of leaves. They hatch in about 3-5 days.
Larvae: The larvae are elongated and spiny, with black and orange markings. They look very different from the adults and are often mistaken for pests. They emerge from the eggs and seek out pest insects to feed on, such as aphids, scale insects, mites, and mealybugs. They are voracious predators and can consume up to 400 aphids during their larval stage. There are four molts before they pupate.
Pupae: The pupae are yellowish and oval-shaped and are attached to the host plant or other nearby surfaces. They are inactive and vulnerable to predators and parasites. Within several days, adults leave the pupal case.
Adults: The adults are the most recognizable stage of the Asian lady beetle. They have a smooth and oval body with a variable color and spot pattern. They have a black “M” or “W” marking on their pronotum. They have two pairs of wings: a hard outer pair that covers the body and a soft inner pair that is used for flying. They can fly up to several kilometers in search of food or shelter.

How They Reproduce

Asian lady beetles reproduce in early spring or summer when the temperature and food supply are favorable. Females can mate multiple times with different males and store the sperm in their reproductive tract. They can lay up to 1000 eggs in their lifetime, depending on the availability of host plants and pest insects.

Conditions Conducive to Survival

Asian lady beetles are adaptable insects that can survive in a variety of habitats and climates. They prefer warm and humid conditions and are active during the day.

In Nature: They spend most of their life in agricultural fields, orchards, gardens, forests, or other natural areas where they feed on pest insects such as aphids. They are beneficial insects that help control the population of these pests and reduce the need for chemical pesticides.
In a Structure (around a structure): Asian lady beetles are attracted to lighter colors: whites, grays, yellows. So, light-colored structures, especially on hillsides in forested areas, might serve as “homing beacons” for them. In fall, they move indoors to overwinter, crawling along windows and walls. Small cracks around windows and door frames provide entry points for them. While indoors, the pests search for moisture or humidity and bask in warm portions of the structure when possible.

Where They Live

The Asian lady beetle is native to Asia but occurs in many areas of the United States. This beneficial insect was imported and released as early as 1916 in attempts to naturally control certain insect pests such as aphids and scale insects on crops such as pecans, apples, alfalfa, wheat, cotton, tobacco, etc. However, it was not until the 1980s and 1990s that they became established and widespread across North America. Since then, they have been expanding their range and population size, sometimes displacing the native lady beetles or competing with them for food and habitat.

How They Winter

Asian lady beetles are cold-blooded insects that cannot survive freezing temperatures. In fall, they seek shelter in warm and protected places to overwinter. They often aggregate in large numbers on the sunny sides of buildings, trees, rocks, or other structures. They can enter homes through cracks, gaps, or openings around windows, doors, eaves, soffits, attic vents, and other likely points of entry. They do not feed or reproduce indoors, but they can become a nuisance by crawling on walls, ceilings, furniture, or people. They can also stain surfaces with their yellowish fluid that they secrete from their leg joints as a defense mechanism. They can also emit a foul odor when disturbed or crushed. Some people may experience allergic reactions to these secretions, such as skin rashes, eye irritation, or asthma attacks.

Evidence Found During Inspection

These pests will be evident when arriving at a property. They will be seen flying around the exterior of the structure and if the population of Asian lady beetles is large enough, then the homeowner might be finding them on the inside of their home. Besides hanging out around the south and west sides of a structure, common places to see these pests congregating around windows, doors, eaves, soffits, attic vents, and other likely points of entry. They can also be found in wall voids, attics, basements, crawl spaces, or other secluded areas where they hibernate until spring.

Fun Facts

Asian lady beetles do not feed or reproduce indoors
They cannot attack the structure, furniture, or fabrics
They do not carry diseases or have the capability to sting although they will “pinch” exposed skin
As a defense against predators, the beetles secrete a foul-smelling yellowish fluid from their leg joints when disturbed
Currently, Asian lady beetles appear to have few natural predators
Structures or buildings shaded from the afternoon sun are less likely to attract Asian lady beetles

If Asian lady beetles are giving you any trouble, call the Experts Today for an honest quote and evaluation to meet your specific needs!

Kwik Kill Services to control Asian Lady Beetles:

Additional Information:

https://ipm.ucanr.edu/natural-enemies/multicolored-asian-lady-beetle/
https://hort.extension.wisc.edu/articles/multicolored-asian-lady-beetle/
https://ohioline.osu.edu/factsheet/ENT-44