Invasive Species Profile: Multicolored Asian Lady Beetle


Invasive Species in Minnesota: Asian Lady and Japanese Beetles, Buckthorn, and Emerald Ash Borer

Invasive species such as Asian lady and Japanese beetles, buckthorn, and emerald ash borer are wreaking havoc on Minnesota. Learn how these creatures may be negatively impacting your home, yard, and community.

MN Invasive Species Profile: Asian Lady Beetles

Multicolored Asian lady beetles (Harmonia axyridis), not to be confused with Japanese beetles, are native to eastern Asia, and were “formally” introduced to the United States in California, by the U.S. Department of Agriculture in 1916. Asian lady beetles are part of the coccinellid family, which is not only indicated by their bright colored wing covers, but also by their voracious appetite for aphids.


Adult multicolored Asian lady beetles are approximately 7mm (1/3”) in length and have a characteristic “M”-shaped marking on their heads. They can vary in color and number of spots, from light orange with no spots to red with nineteen spots. Usually, you don’t know you have a lady beetle “problem” until you actually see the little guys flying around.


While Asian lady beetles were introduced in 1916, they were introduced again in 1964-65 to control pecan aphids. From 1978 to 1982, Asian lady beetles were released in Connecticut, Delaware, Georgia, Louisiana, Maine, Maryland, Mississippi, Ohio, Pennsylvania, and Washington for biological control purposes. The released beetles were not recovered, and thus spread. Asian lady beetles were never introduced to Minnesota for biological control measures they just traveled here and were first documented in November 2004.


Multicolored Asian lady beetles are most prominent in the fall and spring, when cooler temperatures swiftly change to and rise above 65 °F. In the winter, these beetles take shelter in cracks and gaps in housing structures and remain dormant until their environment gets warmer. The bugs you see in your house aren’t spawning; they just house there and get trapped inside buildings when winter arrives.

Why (raise awareness)?

Asian lady beetles don’t do much harm to plants, but they are major nuisances to the general population in their homes and workplaces. These beetles are known to bite. Their bites aren’t lethal by any means, but it will be uncomfortable like a mosquito bite. They also don’t smell very nice when you squish them, and dead beetles have historically caused allergic reactions to some people.

How (can I tell if my lawn is infested)?

Your lawn won’t really see damage, but you’ll definitely notice an infestation in your home. You can tell you have a lady beetle problem because you can see them.

Preventing an infestation is as simple as repairing cracks or holes in your walls, resealing doors and windows, and repairing window and door screens. If you aren’t able to prevent the beetles from coming in, vacuum them up.

The University of Minnesota Garden Extension suggests this simpleand effectivemethod of beetle removal via vacuuming:

how to get rid of asian beetles
Source: University of Minnesota – Extension

Figure 1. A nylon stocking inserted into a vacuum cleaner extension wand creates a handy bag for capturing lady beetles. Options also are to (A) rubber band a piece of nylon over the flexible hose to prevent lady beetle entry into the vacuum cleaner, (B) secure a nylon stocking (open at both ends) inside the foremost section of the wand to somewhat cushion the lady beetles and prevent staining. Diagram courtesy of Ohio State University Extension.


MN Invasive Species Profile: Japanese Beetles

Compared to several years ago, Japanese beetles have fallen out of the news. However, they can still be found in the Twin Cities.


Japanese beetles (JB) are a species native to northern Japan, notorious for feeding on and destroying the roots of more than 300 plant species. The first record of Japanese beetles in the United States was in New Jersey in 1916. Numerous cases have been reported in the Twin Cities.


Adult JBs have a dark metallic green head and dark metallic tan wings. Fully grown, these insects are about 3/8”. Larvae and adult JBs are detrimental to plants in different ways. The larvae feed on the root plants and the adults feed on the leaves of plants, working their way between the leaf’s veins.


Japanese beetles have not made their way across all of the United States, but you can find them localized in certain states (Minnesota, Georgia, and Maine to name a few). JBs are not picky insects; their palates can handle over 300 plant species, from maple trees to rose bushes.


You will start to see JBs in early summer and stop seeing them by the end of August. However, while you won’t see the beetles, the larvae feed on roots and soil the rest of the year.

Why (raise awareness)?

A voracious appetite for hundreds of plants makes Japanese beetles a threat. If a plant is exposed to JBs in addition to other stress (storms, drought), it is unlikely the plant will be able to recover.

How (can I tell if my lawn is infested)?

Due to the way adult Japanese beetles eat leaves, it is relatively easy to recognize infestation. Your plant’s leaves will be intact, but skeletal. If you have turf grass in your lawn, you may notice unhealthy spots in your yard.

To learn more about Japanese beetles in Minnesota, visit the University of Minnesota’s Extension page on Japanese beetles.

MN Invasive Species Profile: Buckthorn

Another common noxious species in Minnesota is buckthorn. Not only is buckthorn toxic to many animal species, but spreads easily and is essentially impenetrable.


Buckthorn is a species of shrubs/small-sized tree and was initially used to create hedges and other types of landscaping. The plant can grow anywhere from 3 to 30 feet in size.


Buckthorn grows mostly in the Northern Hemisphere and is typically contained to North America and Asia. Common and glossy buckthorn are the two invasive species of buckthorn that can be found in Minnesota, usually along the road, in forests, and backyards.


Records indicate buckthorn was brought to Minnesota in the 1800s to be used as natural hedges between properties. Minnesota nurseries stopped selling buckthorn around the 1930s. Buckthorn is most noticeable in the late fall, because its leaves stay green longer than other surrounding plants.

Why (raise awareness)?

The usefulness of buckthorn as hedges is offset by its detrimental effect on native species. Buckthorn grows densely and aggressively, often outcompeting other nearby plants. The foliage is quite full, preventing sun from reaching the ground and depriving grasses and other small plants the ability to get necessary energy from the sun. As if those qualities weren’t bad enough, buckthorn seeds are tough, and can stay viable for years outside of soil.

How (can I help?)

The best way to defeat the spread of buckthorn is through consistent maintenance. In order to successfully remove buckthorn from your property or designated area, you must remove the entire plant – roots and all. If the shrub has berries on it, you need to take extra precautions to minimize the amount of berries that fall to the ground.

Check out the Minnesota Department of Natural Resources website for more information.

MN Invasive Species Profile: Emerald Ash Borer

Ash trees are highly utilized. They can be found across multiple cities in the United States and are often sources for firewood, creating baseball bats, bows, acoustic guitar bodies, and hand tools. Ash wood is dense, but very elastic, making it an ideal resource to have available. Unfortunately, the introduction of the emerald ash borer put ash trees in crisis.


The emerald ash borer (EAB) is thought to have come to North America in a wood shipment from East Asia.


EAB is a metallic green beetle that usually doesn’t grow much larger than 1/3” (8.5 mm). In terms of being detrimental to ash trees, the adults don’t damage the tree as much as the larvae. The larvae feed on the inner bark of the tree, disrupting the channels for water and other nutrients. Since the tree doesn’t get the sustenance it needs, the ash tree begins to decay from the inside out.


The EAB population is quickly spreading across the United States, primarily in the Midwest region. More than 20 states are labeled as “quarantined” and cannot transport ash tree firewood across state lines.


The first reported case of EAB in the United States was June 2002 in Michigan. According to the Minnesota Department of Agriculture, the first confirmed case of emerald ash borer was May 14, 2009, in St. Paul.

Why (raise awareness?)

The emerald ash borer kills ash trees, and Minnesota has the nation’s largest volume of ash trees. Not only is our environment at risk, but our local economy as well. On a residential level, an ash tree that has been compromised by EAB will lose its structural integrity, resulting in a potentially dangerous break in the tree under windy conditions.

How (can I tell if my emerald ash tree has been infected)?

Signs to look for on your ash tree include:

  • Increased woodpecker activity at the tree (woodpeckers love EAB)
  • Bark cracks that expose s-shaped patterns and “galleries”
  • D-shaped holes appear in the tree’s bark during spring

To learn more about EAB in Minnesota, visit the Minnesota Department of Agriculture website.

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