Deep inside an apple, a tiny worm-like creature called the codling moth can destroy an entire harvest. For apple growers in Michigan and Ohio, knowing exactly when these pests arrive in their orchards has always been a guessing game. Now, researchers at Michigan State University have found a better way to spot them — and it works up to a week faster than the old methods.
Codling moths are one of the biggest threats to apple crops worldwide. If farmers do not catch them in time, the insects burrow into fruit and ruin it. Growers normally watch for moth flight using pheromone traps, which are checked once a week, and combine that with weather forecasts to decide when to spray insecticide. The problem? A single week is a long time when moths are on the move.
A research team from Michigan State University's Department of Entomology decided to test a newer tool: automated camera traps, branded as CropVue. These cameras sit in orchards year-round and snap pictures constantly, watching for moth activity the way a security camera watches a building. The researchers placed them in commercial apple orchards in Michigan and Ohio and compared what they found with traditional weekly pheromone traps.
The results were striking. The camera traps picked up codling moth activity three to seven days earlier than standard traps. Weather-based prediction models, by contrast, ranged wildly — sometimes guessing the moths would arrive seven days too early, other times showing them 12 days late. The team analyzed data from 599 monitoring sites across the region to confirm the pattern.
Those extra days matter more than they might sound. Insecticides, especially newer "reduced-risk" chemicals that are gentler on the environment, often need to be applied within a narrow window to work properly. Spray too early and the product fades before the pests appear. Spray too late and the moths have already damaged the fruit. Even a shift of two or three days can mean the difference between a healthy crop and a lost one.
"By improving how precisely we detect when codling moth activity actually begins, we can better align management decisions with what's happening in the field," said Heather Leach, one of the researchers. "That means growers can time sprays more effectively, reduce unnecessary applications and make better use of softer chemistries that depend on precise timing."
The researchers hope that widespread use of camera-based monitoring could eventually improve pest forecasting systems for apple growers everywhere. Michigan alone produces hundreds of millions of pounds of apples each year, making it a vital crop for the state's economy. Tools that protect that harvest while also cutting down on unnecessary pesticide use could benefit farmers, consumers, and the land alike.