More large flights of moths were reported across Iowa last week. In fact, the statewide weekly totals for both true armyworm (TAW) and black cutworm (BCW) far exceeded those of previous weeks. Across the state, our cooperators reported a total of 243 TAW moths and 188 BCW moths between May 17 and May 23.
Several additional significant flights occurred in south-central and western Iowa last week. Although we have already predicted cutting dates for BCW based on significant flights that occurred in April, we suggest using the estimated cutting dates as a baseline for scouting.
With updated degree day information, predicted cutting dates could extend through June 10 across the state. It is likely that cutting has begun in southeast Iowa (climate division 9). Continue to scout fields weekly until V5 to account for any prolonged arrival of BCW larvae into the area. If you see BCW larvae or evidence of feeding, please email firstname.lastname@example.org. This can help us refine our predictions in the future.
Figures 1 and 2 show the total moth captures in each county from May 17 to May 23 for TAW and BCW, respectively.
Surrounding states also monitor and report BCW and TAW captures. If you live near the state border, it may be beneficial to check these resources periodically. More resources may be available than what is listed here: