Pest Monitoring: The Numbers Tell the Story

Monitoring pest activity has been a part of Integrated Pest Management (IPM) programs for many years. Monitoring is the tracking of pest captures or sightings over time, allowing you to detect changes in activity, population numbers and immigration patterns. These numbers can help you tell a story.

Your customers want the numbers, but they also want to know what the numbers mean. They want a story. Looking beyond the actual pest counts, or the numbers, can tell a story of what is happening in their facility.

Almost any device that traps a pest can be used as a monitor. Remember that capturing a pest is trapping; writing down what you capture is monitoring. Today, there are many trapping devices for insects and rodents. For insects, we have sticky traps, food-based traps (e.g., fly bags), pheromone traps and light traps. For rodents, we have glue traps, snap traps, multi-catch traps, electrocuting traps and even bait stations.

All of the numbers are important in the quest to understand pest activity. The pheromone trap in a corner that never catches anything is as important as the one that captures insects every service. A zero-capture is not nothing; it is a number and a data point. Knowing there are no insects in an area is as important as knowing there are dozens.

TECHNOLOGICAL ADVANCEMENTS. Recently, numerous devices have been created that detect activity electronically and, in some cases, will even count the captures electronically. Technology can make our jobs easier, but it should also make us more effective. We need to think about how to get more information from our monitoring programs to make us more effective in preventing, finding and eliminating pests.

Devices count the number of insects in a light trap, and pheromone traps help with accurate data collection, but can they do more?

Can we draw better conclusions based on the activity we see?

To gain the most information from a monitor, you must understand the capabilities and limitations of the device, as well as the biology and behaviors of the pest it is capturing.

Pheromone traps are an example of devices whose captures are determined by an insect’s biology. A stored product moth’s biology and behavior is different than a beetle’s biology and behavior. Moth larvae leave their food source before pupating, while beetles, such as cigarette beetles, do not. This means emerging adult moths are always flying in the environment between generations, while beetles may not be flying. This simple fact means that you are much more likely to capture moths at low infestation levels than beetles.

IMPORTANT DIFFERENCES. When telling the story of moth or beetle activity, consider these differences. A threshold or response may be different for the same capture numbers with different insects. For example, based on their behavior, a sudden increase in moth captures may indicate the arrival of infested product, while a sudden increase in cigarette beetles may indicate a maturing infestation in products already in the facility.

More information is needed to confirm these conclusions, but this is what customers want to know. This level of investigation and analysis is what is needed — not merely a list of numbers of insects captured in each trap. But what do those captures indicate about the source or the level of insect activity? Ultimately it allows the customer to evaluate their risk from the insects.

This is what a professional does — tells the story.

Jeff Weier retired in 2020 after 36 years at Sprague Pest Solutions. Currently, he is a consultant specializing in pest management in the food industry and stored product pests. He has authored several book chapters and numerous articles on these topics, including the stored product pests chapter in the Mallis Handbook of Pest Control. Weier is a founding member of the Urban Pest Management Technical Committee.