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Entomologist encourages growers to be on the lookout for wheat and alfalfa pests

by Wyoming Livestock Roundup

During an episode of Kansas State University’s (KSU) Agriculture Today podcast, dated Dec. 18, Host Eric Atkinson sat down with KSU Crop Entomologist Dr. Jeff Whitworth to discuss insect prospects during mild winter conditions. 

Although damage done by insects is usually minimal this time of year, Whitworth notes growers should be ready to take action against a few different species to prevent considerable damage to their crops. 

Winter green mites

            “The arthropods we get the most calls on in regards to winter wheat are winter green mites,” Whitworth explains. “Winter green mites are small – they can barely be seen with the naked eye. They have a red-orange spot on their back and they have red-orange legs.” 

            Whitworth further explains the particular insect is most active at nighttime or on cloudy days when temperatures are around 45 to 60 degrees. He also notes winter green mites feed on the individual cells of wheat plants, creating a silvery appearance. 

            “We have had a very mild winter this year, so we have seen more mite activity than usual. Right now it isn’t much of a problem because wheat is in dormancy anyway,” he says. “However, if spring rolls around and we still don’t have good growing conditions, coupled with a lack of moisture, the built up population of mites we are seeing now will still affect our wheat when it breaks dormancy. This will set it back considerably.” 

            On the other hand, Whitworth notes another cold spell or a wet spring will help growers get rid of the mites.

            “Once our winter temperatures get back to the usual 30s and under, the mites will retreat into the soil, and they will no longer be a problem,” he says. “Likewise, if we get good moisture, wheat will outgrow the damage and the mites will be gone.” 

Army cutworm

            While winter wheat producers keep their eyes peeled for winter green mites, Whitworth encourages alfalfa growers to do the same for army cutworms.

            “Last spring we had the worst army cutworm infestations I had seen in 20 years,” he states. “I have heard from several growers, they are back this year but we don’t know if they will be as big of a problem as they were last year.” 

            Whitworth points out at this point in time army cutworm larvae are nearly one-fourth of an inch long.

            “Right now they are too small to eat an entire leaf, so they will only eat the front or back side,” he explains. “This causes a window pane effect. So, if growers start to notice their leaves are looking slightly transparent, they should dig around and sample for larvae.” 

Alfalfa weevil

            In addition to army cutworm, Whitworth also suggests alfalfa growers be on the look out for alfalfa weevil.

            “Last year we found alfalfa weevil larvae clear up until November. Weevils usually overwinter as eggs or adults, but conditions might be mild enough this year that they successfully overwinter as larvae,” Whitworth explains. 

            With this said, Whitworth highly suggests growers get out and sample their fields. If there is a 50 percent infestation or greater, he encourages producers to consider treating their alfalfa.

            “However, if the weather forecast is calling for temperatures around 20 degrees or below, I recommend not treating and simply letting Mother Nature help out,” he says.

            Hannah Bugas is the editor of the Wyoming Livestock Roundup. Send comments on this article to

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