Spring ushers in a new batch of curious bugs

Friday, April 11, 2003

They appear silently and suddenly around your home or office.

They cluster in corners, doorways and windows, hundreds of them in one spot. They swarm around your head, falling on your head or in your food.


You've heard the stories about ladybugs: that they're good bugs that eat bad bugs, or that it's bad luck to kill them. You know they're harmless, but let's face it: The thought of anything swarming in your house is, well, kind of creepy.

Some of you have heard these are not ordinary ladybugs. So the questions are: What are these bugs, are they as good to have as our regular ladybugs and why are they here?

First, unless you're in your early teens or younger, these aren't the ladybugs you grew up with. The ladybugs that cluster inside your house are multicolored Asian lady beetles (Harmonia axyridis). They are native to Asia but occur in many parts of the United States today.

Sometimes it may be difficult to figure out whether the lady beetles you are seeing are multicolored Asian lady beetles or another species. This is because they have a wider range of color and numbers of spots than any other type of lady beetle. In the U.S. the most common type of multicolored Asian lady beetle is colored mustard yellow to red with 16 or more spots. Still, they may range from black to mustard to red with zero spots to many spots.

One feature all multicolored Asian lady beetles have is the large white football-shaped markings behind the head. These markings look similar to eyes and may help scare away predators.

Second, they are incredibly beneficial. Like our native lady beetles, the multicolored Asian lady beetle eats many insect pests in orchards, fields, row crops and gardens. Their diet focuses on aphids and other soft-bodied pests and includes more than 50 species. They commonly feed on pests that affect ornamental roses, peaches, apples, magnolias, clover, cabbage, vetch, pine, tulip trees, maples and other plants.

They are massively big eaters, and both lady beetle larvae and the adults eat pest insects. It is believed that one lady beetle larvae can consume 300 aphids during the 15 to 25 days it takes to reach adulthood. In fact, they are so beneficial that beginning in 1916, federal, state and private insect biologists (entomologists) tried to introduce them to our country for years. Individuals also accidentally entered the country via sea ports in Delaware and South Carolina. However, until 1988 it was believed that these lady bugs had not established a population in the U.S. Then some were found near New Orleans. From there they spread rapidly over much of the country.

If there are ladybugs swarming your home, you may want to know other things, such as: What are they doing in my house; can they cause any damage; how do I get rid of them?

When the weather begins to turn cold, they look for a place to cluster, or aggregate, during the winter months. They are attracted to areas that are sunny, light colored and have cracks and crevices where they can crawl to escape from cold wind and storms. This may be rocky outcrops, grain silos, brick walls or even siding. Often they will remain inside the walls, and you will never know that you had visitors through the winter.

Sometimes, though, they are attracted to the warmth and light coming from inside the house or are flushed out as spring arrives. If this happens, they may move inside. They will not do structural damage to your house.

They won't eat your furniture or lay eggs in the house. However, it may be a bit unsettling to see such a big cluster of these insects inside your home. It takes careful handling to remove them. When lady beetles become agitated, they secrete an orange-yellow liquid -- which actually is their own blood -- from their leg joints. It's smelly and tastes awful. This action is called reflex bleeding and is a defense mechanism. All lady beetles, including multicolored Asians, do this when they face agitation.

While the liquid is harmless, it can cause staining on walls or fabrics. For that reason, it's not a good idea to pick them up or squash them. Spraying them with insecticide isn't a great option due to their beneficial nature. So how do you get rid of them?

The easiest solution is to prevent them from entering your house in the first place. Caulking exterior cracks and crevices during the summer or early fall will prevent lady beetles from entering. In addition, it will keep out other unwanted pests like wasps and flies. It also will help lower your heating costs.

Once they've entered, the best thing is to vacuum them with a crevice tool or hose attachment. You can then release them outdoors. If it's still cold outside, try to release them somewhere where they can get protection from the cold. Otherwise they may die.

Another option for children is to put the lady beetles in containers in the refrigerator. Once a week, pull them out so they can get warm, and give them a little sugar water so they don't dehydrate. Then when warmer spring weather arrives, you can release them outside without any worry for their safety. Children can learn about the lady bugs and exercise responsibility.

Lady beetles, whether multicolored Asians or other species, are wonderful additions to our gardens, orchards and fields. They provide thousands of dollars of free pest control every year without pesticides. They also provide hours of joy to children and adults who share gardens with them. The only downside to this cheery little insect is that they also like to share our warm homes with us.

If we do a little planning, this won't be a problem either. What could be better than a great little bug with benefits to the plants we love?

Joe Garvey is a forestry supervisor with the Missouri Department of Conservation.

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