DECATUR, Ill. — Crop scouting and understanding pest pressure is critical to maximizing yield potential, and a convenient tool is available to aid in the effort.

An online insect forecast tool, developed by climatologist and meteorologist Mike Sandstrom, helps farmers understand their current pest pressure and make more accurate predictions of future migration.

Farmers can log on to www.insectforecast.com to learn when corn rootworm larvae are hatching and to track the migration and moth flights of two damaging above-ground insects, corn earworm and western bean cutworm, throughout the growing season.

With online and mobile access, this tool is useful to better understand when potential root damage may occur and to help farmers with their scouting efforts.

“The tool gives the grower a proactive approach to insect management issues,” Sandstrom said.

“We provide a one-day, two-day and three- to five-day lead forecast, so the grower can have an idea of what kind of pressure they can see specifically for corn earworm, corn rootworm and western bean cutworm across the corn-growing region from east of the Rockies all the way to southeastern Canada, so a grower in any geography can see what the risk is in their specific location.”

Farmers in the Corn Belt can sign up on the website to receive email alerts from May through September to learn when these insects pose a risk in their area.

In 2012, more than 5,000 farmers visited the Insect Forecast site to identify when damage may occur to their corn crop and to make vital decisions for the following year.

The Insect Forecast tool analyzes moth trapping data and weather patterns. The corn rootworm hatch is updated weekly and is based on soil temperature and Growing Degree Days across the Corn Belt.

The Insect Forecast tool is being sponsored for the fourth year by Monsanto and offered to farmers by its Genuity brand.

“This is a free service to anybody. They can sign up to get alerts of when they can see an increased risk of insect pressure throughout the growing season,” Sandstrom said.

Data used in the insect forecast is collected by growers and agronomists scouting fields, as well as academia.

“I work very closely with a lot of the land-grant universities and the entomologists that I know,” Sandstrom said.

“I get their trap counts and what they’re seeing in the field and then from private sources, as well. Pest Watch through Penn State University is another source, as well, for trap data, so I know what kind of pressure is out there in the fields, and then I take the weather and tie those two together to make a probabilistic forecast.”

The width, direction and speed of insect migration are based on a number of factors and also depend on the insect.

“With corn earworm, specifically, that is a migratory pest because they cannot survive most Midwest winters, so they have to fly up from the south,” Sandstrom said.

“Corn earworms are always present south of Interstate 40, so it takes a very specific weather pattern, usually with a high pressure in the east coast and then a low pressure somewhere in the plains, and in between those two pressure centers you usually a nice southerly wind. That southerly wind is what blows the insects to the north.

“The second key component is where is the crop stage in the mid-south where the source region is and also further north. As the season progresses, we usually see corn earworm flights increase because the crop is becoming less favorable to earworms in the south and they fly to the north in order to survive.”

Weather events such as the remnants of a hurricane move northward also have brought pests with it.

“In 2005, we had a hurricane come up on July, and that did bring up a number of corn earworms and increased the pressure,” Sandstrom said.