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Biological control methods consist of using one particular non-native organism to control the proliferation and geographical spread of an invasive pest-organism within a particular region. Biological control methods often entail the import of a particular exotic insect species into a non-native region in order to allow it to destroy an invasive insect or plant species in the same region and under controlled conditions.

As you can imagine, the history of biological control projects are comprised of many disastrous failures. For example, ladybugs are one of the most common insect pests within homes, and the most common ladybug pest in America is the Asian lady beetle. Surprisingly, these common insect pests are not native to North America. In fact, these insects were deliberately brought into the United States from Europe in order to allow them to eradicate crop-infesting invasive insects as an early biological control method in the US. Unfortunately, the project leaders quickly lost control of the exotic ladybug’s reproduction rates and the insects rapidly spread across America, invading homes and upsetting North American ecosystems.

This particular biological method to eradicate invasive crop-pests only resulted in the introduction of an additional invasive pest into America, but unlike the original crop-feeding invasive insects, the ladybugs are pests to structures more so than pests to crops and wild plantlife. Asian lady beetles gravitate toward homes in an effort to secure a warm indoor location before the cold of winter sets-in. Therefore, the survival of these ladybugs depends on whether or not they can successfully enter a home or building in order to overwinter.

Although the Asian lady beetle arrived in America from Europe, this insect species originated from Asia. Before this ladybug species became a problem within people’s homes, researchers found that these relatively aggressive ladybugs prey upon and kill entire populations of native ladybug species. Resulting in damage to the ecosystems where these ladybugs are invasive.

Did you always assume that ladybugs were harmless to American ecosystems considering their relatively positive reputation among humans?