The compilation of 2001 black light trap captures of corn earworm (cotton bollworm) moths represents our 13th annual summary of primarily major third (F2) generation activity. This information provides comparisons of moth catches from area to area and from year to year, resulting in a better understanding of the timing and magnitude of these major flights, and their impact on egg deposition and larval establishment on cotton, soybeans, and peanuts.
Almost all black lights utilized in this survey are the General Purpose Insect Survey Traps (old Ellisco design, Old Boys Enterprises, Inc., Model T-2020; now, Gempler’s™ Item No. RAB111). Most traps are suspended from a 4 inch by 4 inch by 3 ft treated crosspiece held up by two 4 inch by 4 inch by 10 ft treated side supports typically placed into the ground to a depth of 24 to 36 inches. This results in having the middle of the UV tube (black light) and the galvanized trap vanes being approximately 5 ft from the ground. We recommend that trap checkers suspend ⅓ to ½ of a Pest Strip® (Vapona) within the collection bucket of the trap to both minimize escapes of live moths and to more quickly immobilize beetles and other insects which renders the captured moths to be more difficult to identify. Additionally, the 4" by 4" crosspiece can be covered with a piece of ½ inch exterior plywood (4 ft. by 4 ft.) to reduce the amount of water which may get into the traps. Some traps have internal water excluders which serves to keep traps dry, while others have small drainage holes drilled into the bottoms. Traps are best located within a large open area away from mercury vapor lights and adjacent to row crops including field corn and cotton.
Although most of our cotton-related black light traps are monitored on a Monday-Wednesday-Friday schedule from approximately mid-July through late August or early September, information in certain counties has been gathered on either a more or less frequent interval and/or over a longer or shorter period of time. In 2001, moth counts from 16 traps were available online at our web site (http://ipm.ncsu.edu/cotton/insectcorner), sometimes with a few hours of the traps being checked.
In the figures, all X-axis (month and days) are identical for figure uniformity. Each dot represents a count, with the count divided by the number of days between counts. Therefore, all counts are expressed on a per night basis. For example, Monday counts, typically representing moth captures from the previous three nights, are usually divided by three, Wednesday and Friday counts divided by two and counts from traps checked every day were not changed. The "peaks" listed are somewhat arbitrary, in that they usually expressed an average of two or three nights' catches (not a given night) and are placed on the date the trap was checked. Listed peaks, then, should be within a day or two prior to actual peaks. Additionally, a flight peak could have occurred either prior to or following the trap checking period, particularly if a given trap were monitored for a short period of time. If more than a 4 day lapse occurs between checks, an “X” is put on the graph to show that a check date was missed and no report was given. Note also, that the various graphs were not constructed at the same scale for the Y- axis numbers (number of moths). Thus the highest points of the Y- axis on two separate graphs, for example, one might be 50 vs. another at 500 moths per night.
We are hopeful that this data will be helpful in providing recorded historical light trap information on the flight activity of corn earworm moths from the participating counties.
This past year was characterized by late and low bollworm moth flights. Thus, this year was similar to 1999. Adult vial testing for bollworm resistance to pyrethroids revealed low moth survival, encouraging after the relatively high survival found at a few locations in 2000. Nevertheless, it is still extremely importance to both avoid pyrethroid use early (for the June to early July budworm generation) and to use alternatives to pyrethroids for corn earworms in soybeans and peanuts.
We wish to thank the county agents, consultants and producer cooperators listed in the following tables who either provided a light trap station area and/or passed along these moth counts to producers and consultants.