How sweet it is to control German cockroaches


July 5, 2023

Photo: Gene White

Photo: Gene White

Have you ever found yourself battling a German cockroach infestation that wasn’t showing any signs of retreat?

You followed your tried-and-true integrated control protocol to the letter. You even rotated baits to introduce a new active ingredient and mode of action to the lineup to combat possible resistance issues, but still no luck.

It’s possible this was a population of Blattella germanica that were exhibiting unique changes to their feeding preferences that have evolved in recent decades.

As is the case with many other structural pests, insecticide resistance is well documented in German cockroaches. In fact, this species has been reported to have developed resistance to more than 40 different active ingredients, making it one of the world’s most resistant urban pests.

Even more frustrating is that, unlike other structural pests, the German cockroach also has developed a unique behavioral resistance mechanism that can render some cockroach baits relatively ineffective.

German cockroaches are scavengers that will feed on a wide range of human foods. This is especially the case with foods containing glucose, a simple sugar found in sweets, fruits and many other natural and processed items. Because of their fondness for glucose, many cockroach baits incorporate this sugary treat to act as a food attractant and encourage feeding activity.

Dr. Michael Bentley, BCE

Dr. Michael Bentley, BCE

In the past decade or so, researchers discovered that some German cockroach populations will exhibit a distinct avoidance of glucose-rich substances. This evolutionary adaptation enables the cockroaches to avoid baits formulated with glucose. Fortunately, there are alternative baits available that are specifically designed to address this unique behavioral resistance.

So, the next time you find yourself up against a particularly stubborn infestation of German cockroaches, pause to observe the feeding response of the cockroaches to your baits. If you deploy a bait containing glucose and you observe any avoidance behavior, it may be time to try a different product formulated with an alternative food attractant.

About the Author

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Dr. Bentley is director of training and education for the National Pest Management Association. You can reach him at

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