2024 University of Minnesota Cooperative Black Cutworm Trapping Network
Report #1 March 29 to April 12, 2024
For more information: https://z.umn.edu/bcw-reporting
April 15, 2024
Greetings:
March 29 was the official start of the 2024 black cutworm (BCW) moth trapping season.
The arrival of black cutworm moths in 2024 is right on schedule. Cooperative Black Cutworm Trapping Network results from 2012 to 2023 show that the earliest arrival detected was March 30, 2021, and the latest was April 13, 2021.
The red admiral butterflies, another migrating insect, in my yard last Sunday indicated weather systems were favorable for migrating insects - including some of our crop pest species. Indeed, some BCW moths took advantage of the same strong southerly winds.
Numerous cooperators traps reported captures from April 6 on. The number of moths captured has been low. The exception was a Brown County trap where an 8-moth capture occurred on April 8 (Figure 1, Table 1). This is a significant capture. The network has been using 2 moths captured over a 2-night period as an indication that a large migration has occurred and an increased potential for crop damage. We can use the moth arrival date, or biofix, and degree to predict the timing of egg hatch and onset of leaf feeding, when larvae are large enough to cut corn, and when the BCW larvae will quit feeding and pupate (Table 2).
The BCW moth is looking for sites with winter annuals and early spring emerging annual weeds to lay their eggs. Tillage disrupts this weed growth and makes a field less attractive for egg-laying. For BCW management, it is helpful to record when early season vegetation is terminated by tillage or burndown herbicide.
True armyworm (TAW)
As of April 12, 2024, no true armyworm moths have been captured.
TAW larvae feed on grasses. Areas of dense grassy weeds in row crops, lodged grasses and small grains, and winter cereals are attractive egg-laying sites. Later this season, these will be areas to focus scouting on.
If you want to learn more about armyworm management, see Armyworm in Corn. In future issues, I will go through aspects of BCW migration, scouting, and management as the season progresses.
This project is supported, in part, by the farm families of Minnesota and their corn check-off investment.
Until next week,
Bruce Potter