Northern Corn Rootworm Beetle
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Northern Corn Rootworm Beetle
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Wisconsin corn growers could catch a much-needed break in 2027, as early field surveys point to a sharp decline in costly corn rootworm populations.
Krista Hamilton, an entomologist for the Department of Agriculture, Trade, and Consumer Protection, tells the Mid-West Farm Report the pest is a massive financial drain. “It is the number one insect pest for Wisconsin corn growers, and really, states across the corn belt because it’s the most expensive in terms of control costs and technologies, so growers always want to know the results of this particular survey.”
Hamilton says finding seven to eight beetles across ten corn plants marks a high population threshold. “Our state average right now is about three beetles per ten plants, so we’re less than half of that threshold. We’re looking at pretty low populations right now, and we still have a few more fields to complete, but I don’t know with the number of fields left if it will change that outcome dramatically.”
She calls the preliminary results encouraging. “I’m surprised to see they’re down quite a bit, so we are looking at much lower levels right now, and I do want to preface this by saying our survey is not complete, so we still have a few more counties to get to before we wrap things up, but right now, the numbers are down quite a bit from 2025. We’re seeing lower numbers in at least, so far, eight of the nine districts.”
The Drop In Beetle Numbers is Significant
Wisconsin typically faces its highest rootworm pressure in the south-central and southwest regions. This year, however, Hamilton reports those local beetle populations have dropped by half.
Crop input costs remain high, and Hamilton says growers might be able to save some money on the 2027 crop because of expected lower rootworm pressure. “It means if you’re purchasing seed or if you’re thinking about, you know, can I justify the expense of rootworm technology and considering rotation, it would be a good year to think about some of those options or maybe steering away from some of the expensive options if you can, if that’s a choice, just because we’re expecting lower pressure from rootworm beetles.”
