Cooperative
Extension
Service


University of Illinois
at
Urbana-Champaign


No. 7/May 8, 1998

Intense Black Cutworm Moth Captures Reported from East-Central Illinois

Several cooperators reported intense flights of black cutworm moths during late April and early May in east-central Illinois. Jeff Huffman, Piatt County, found eight moths in a pheromone trap near Bement on April 30, and nine moths on May 1. Aaron Grote, United Prairie Cooperative, trapped 16 moths in a trap located near Arthur, Moultrie County. Moth captures as reported by Jim Morrison, crop systems educator, Freeport Extension Center, have slowed to just a trickle throughout late April and early May. Moths will continue their migration throughout Illinois for the rest of May, so, please continue to pass along your capture information to Kevin Steffey and me.

Table 1 provides some updated projected cutting dates that are based upon intense flights beginning in mid-April and continuing through early May. Don't forget to refer to our earlier projected cutting dates (Bulletin no. 5, page 38) based upon intense flights that took place from mid-March through early April. As you begin to troubleshoot fields for early signs of black cutworm leaf feeding, Figure 1 may be of some use to you. This figure should enable you to determine the age (instar) of black cutworm larvae, the approximatenumber of days left to feed, and the potential number of plants that may be cut. A reminder, don't wait for cutting as a first sign that black cutworm larvae are at work. Your scouting efforts in cornfields that are in the seedling stage of development should concentrate on looking for small, pinhole leaf-feeding injury left behind by "nibbling" early instar black cutworm larvae. As planting delays continue and winter annual weeds flourish in untilled fields, the odds of economic infestations of black cutworm larvae increase. Please let us know if cutting infestations of black cutworms begin to surface in your region of the state. Thanks for your cooperation!

Table 1. Projected date when 300 heat units above base 50 degrees F will have accumulated after the date of an intense capture of black cutworm adults (9 or more moths caught in a pheromone trap during a 1- to 2-day period)

Crop-reporting district and locationDate of intense capture of black cutworm adults
in pheromone-baited traps
4/15 4/174/194/214/234/254/274/295/15/3
Projected date of cutting activity by black cutworm larvae
Southwest
Belleville5/155/165/165/175/175/185/205/215/215/23
Carbondale5/145/155/155/165/165/175/195/205/205/22
Southeast
Fairfield5/155/165/175/175/185/195/215/215/215/23
Rend Lake5/145/155/165/175/175/195/215/215/215/23
Dixon Springs5/115/125/125/135/145/165/185/195/195/22
West Southwest
Perry5/185/185/195/195/195/215/225/225/225/24
Springfield5/185/185/195/195/205/215/235/235/235/25
East Southeast
Brownstown5/185/185/195/195/205/215/225/235/235/25
Olney5/175/185/185/185/195/205/215/215/215/23
West
Monmouth5/205/205/205/215/215/235/245/245/245/26
Central
Kilbourne5/185/195/195/195/205/215/235/235/235/25
Peoria5/205/205/215/215/225/2 5/255/255/255/27
Wildlife Park5/205/205/215/215/225/235/255/255/255/27
East
Bondville5/205/205/205/215/215/235/245/245/245/27
Champaign5/205/215/215/215/225/235/245/255/255/27
Stelle5/185/195/195/205/215/225/245/255/255/28
Northwest
Freeport5/245/245/255/255/265/275/285/285/285/30
Northeast
DeKalb5/245/245/245/255/265/275/285/285/285/30
St. Charles5/255/255/255/265/275/285/285/295/295/30

Figure 1. Head-capsule gauge for determining the age (instar) of black cutworm larvae, the approximate number of days left to feed, and the potential number of plants that may be cut.

Mike Gray (m-gray4@uiuc.edu), Extension Entomology, (217)333-6652