Accidental Orange Invader

Charlie Metz
Frederick County Master Gardener Program

This is the time of the year that an insect invades our homes and creates a lot of annoyance. It is recognized by its orange and black color. It is the Ladybird Beetle. It is called an accidental invader because it comes into our homes for no apparent reason except that it thinks it is a nice place to be.

The Ladybird beetle is the common name given to over 6000 species of similar looking insects. As kids we all remember holding a ladybug in our hand and asking it to fly away because its mother's house was burning down. I don't ever remember wanting to kill this insect because it seemed so harmless. What I didn't know was that it really is quite a beneficial insect. Ladybugs have a huge appetite for aphids and scales, and are quite successful at their control.

The species of lady bird beetle that invades our homes is the Asian Lady Beetle, Harmonia axyridis. This insect was brought here in the 1980s to control the aphid population which gardeners are all too familiar with. This multicolored dome-shaped insect is about one-third of an inch long with a yellow-orange color with 19 black spots. It also has a distinctive W -shape black spot on its head. This is the adult stage that we are familiar with.

The larval stage is the time in a ladybird's life that it eats the most. The larval stage of the ladybird beetle appears to resemble an alligator. It has a segmented body with 6 long legs. It is mostly black with a few orange markings. It has no wings at this stage. A single ladybird beetle can eat up to 5000 aphids in its lifetime, most of them in its larval stage. You may have seen this insect stage before and had no idea it was a ladybird beetle. Don't spray insecticides at this time. The ladybird beetle larvae will take care of almost all of your aphids.

The adult stage is the reproductive stage. The insect has wings so it can fly around and find a mate. The ladybird beetle reproduces a few times each year. She lays up to 300 eggs near a colony of aphids. When the eggs hatch the smorgasbord begins for the larvae.

At the adult stage, the ladybug still eats aphids, but since there really are no aphids around in the fall and early spring, they tend to congregate in windows on the south side of houses. This is when their large numbers can become a nuisance. I don't know how they get into my house, but they come in by the hundreds.

You can leave them alone or if you don't want them around they can be handpicked or vacuumed up. Insecticides are not recommended. These insects are harmless, eating nothing in your house and causing no disease. Whatever you do, they should disappear in a few weeks.

Some preventive measures you can take include planting a shade tree on the south side of your house to eliminate the sunny areas they tend to congregate in. You can also caulk and seal your south facing windows and doors.

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