Black cutworm moths arrived in significant numbers again this week. DATCP’s network of 90 pheromone traps collected 678 moths during the April 25-May 1 reporting period. This is an increase from 565 moths the week before. Intense captures were documented at 26 of the sites. An intense capture of nine or more moths in two nights indicates a large flight has occurred. It also means that a corresponding increase in cutworm egg laying can be expected. The first intense flight also marks the starting point (or biofix) for counting degree days to forecast the peak seedling corn damage window. From the date of an intense capture, an average of 300 degree days (modified base 50°F) is required for the black cutworm to develop from the egg stage to the damaging fourth-instar larval stage.
The black cutworm migrates northward each spring from overwintering areas in the Gulf states. When appropriate weather systems occur, the moths can reach Wisconsin from Texas in only two days. The first moths of the 2025 season were recorded in traps on April 2. The total cumulative count as of May 1 is 1,389 moths in 90 traps. This is an average of 15 moths per trap. This five-week count marks the half-way point in the black cutworm trapping survey and is slightly higher than the 813 moths in 77 traps (average of 11 per trap) captured by the same time last year. A preliminary forecast of starting dates for the 2025 peak seedling corn damage window is provided in the map below. Please note these dates are subject to change if spring temperatures deviate significantly from 30-year normals in the next three weeks.
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