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An Update on Arrival of Black Cutworm in Pennsylvania

An Update on Arrival of Black Cutworm in Pennsylvania
By John Tooker
As reported previously, our Black Cutworm Monitoring Network had detected four significant flights of black cutworm moths in our pheromone traps. Since our report last week, we have added an additional significant flight in Montgomery County, near Souderton. In these areas, one should expect an elevated risk of cutting damage by caterpillars later in the spring. For better or worse, the colder temperatures this week has slowed down caterpillar development.
Table 1:
Nearest municipalityPA CountyDate of flightDegree day 
accumulation by 16 May
UlyssesPotter19 April57
North CornwallLebanonApprox. 19 April230
MontoursvilleLycoming27 April135
LemastersFranklin2 May149
SoudertonMontgomery14 May14
Cutting damage from black cutworm caterpillars tends to occur about 300 degree days after these flights, so the time to scout at any of these locations has yet to arrive (note the degree-day accumulations thus far in Table 1), but could arrive soon in Lebanon County if warm weather returns. For areas not listed, the degree-day accumulations for the closest location can be used to approximate the time to scout, but I usually recommend that fields get scouted every 7-10 days and this “regular” scouting should detect black cutworm damage. When scouting your fields, note that black cutworm caterpillars can damage corn from first emergence up to V4 or V5. For young plant, cutworm damage can look like a series of symmetrical holes through the leaves (Figure 1). Remember that if cutting damage is found, rescue treatments are usually the most efficient and economical tactic for managing black cutworm. For more information, see our black cutworm article .