Pictured: True armyworm moth. Photo by Jordi Badia
This week’s temperature drop was matched by a decline in true armyworm trap counts. DATCP’s True Armyworm Trap Network documented a marked decrease in moth flights. For the April 30-May 6 reporting period, the total count was 1,088 moths in 42 traps (average of 26 per trap), which is considerably lower than last week’s 3,538 moths (average of 80 per trap).
The individual high trap count at Brodhead in Green County fell from 550 moths to 208 moths, as did the number of sites with catches of 100 or more moths. Only three trapping sites caught more than 100 moths this week in comparison to nine sites last week.
Despite the temporary slow-down, the 2026 true armyworm migration has brought high trap counts to several Wisconsin locations. This spring’s cumulative count of 8,274 moths in 59 traps (average of 140 per trap) so far exceeds the 6,537 moths in 53 traps (average of 123 per trap) recorded by the network at the same time last season.
Although these heavy flights rarely produce damaging first-generation larval armyworm infestations in June, they can lay the groundwork for second-generation armyworm problems in July. This was demonstrated in 2025 when heavy armyworm outbreaks developed in western Wisconsin.
At a minimum, this spring’s trap counts are a red flag to continue following armyworm flight reports and to plan regular field checks starting next month. Scouting for larvae in small grains, corn, and pastures approximately three weeks after a large flight is the only decisive way to know if armyworms are an active threat in fields.
Learn more: https://datcp.wi.gov/Pages/Programs_Services/TrapNetworks.aspx
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