Adult black cutworm moths migrate to the Midwest from the Gulf states each spring with the heaviest migration occurring in April and May. Many states (including the WI Dept. of Ag. and Consumer Protection Pest Survey Group) have pheromone trapping programs designed to give producers and crop advisors an early warning. This spring there have been sporadic reports of “concentrated captures” (9 or more moths in two consecutives nights) of black cutworm moths in Indiana, Illinois, Kentucky, Missouri and Wisconsin. Krista Hamilton, DATCP Entomologist, suggested cutting may occur as early as May 21 in the south central counties based on timing of trap captures and projected temperatures. Pheromone traps are an important IPM tool, unfortunately trap captures may not always correlate with field damage. There are additional tools you can use to anticipate and prepared for black cutworms.  For example, identification of early instar feeding injury, knowledge of oviposition preferences and how planting dates affect injury can be useful in concentrating early season scouting efforts. Although not foolproof, this information can then be used to coordinate future scouting activities. 

 

Female moths usually deposit eggs on low growing weeds or the previous year’s weed/crop residue prior to corn planting. Rarely are eggs laid on living crop plants. Low-lying, poorly drained areas are also preferred egg laying sites. Additionally, when given a choice, females prefer to lay eggs in fields with soybean residue over that of corn or wheat.   By knowing and understanding this information we can focus early season efforts on those areas most likely to have damage. 

 

Accurate identification of early instar cutworm damage can also give us an early warning. First through third instars feed nocturnally and above ground, often chewing shot-like holes in the leaves. Although this feeding isn’t considered economic it does indicate fields which may soon experience cutting at or below ground level. 

 

Corn is most susceptible to black cutworm injury during the V1-V4 stages of development. Early planted corn fields may escape injury by missing the majority of migrating moths or by being too mature for larval injury. On the other hand, late planted fields may be more attractive to late migrating moths and suffer greater damage. This may be especially important during the 2008 growing season because we are off to a slow start.    Therefore, the amount of damage may depend on both the timing of migration and planting date.  

 

Black cutworms are an occasional pest on corn and injury can be hard to anticipate. Spring is also a busy time of the year and nearly impossible to scouting every acre of corn. By using pheromone trap catch reports, knowledge of oviposition preference, proper identification of injury symptoms and by having an understanding of migration vs. planting date we can fine tune our scouting practices to spend more time in those fields with the greatest potential of damage and use this information to manage scouting frequency for all other fields.