DEFOLIATORS 

Monitoring European Corn Borer Moth Flight

Gary Hein, UNL Extension Entomologist, Scottsbluff

 To determine exact ECB moth activity, sampling for the insect in a given area is needed. The two methods used are black-light and pheromone traps.

 Black-light traps are the traditional sampling tool. Night-flying moths are attracted to the light and trapped in the funnel-shaped trap below the light.  The greatest benefit of the black-light trap is that it measures moth activity as it occurs. As a result, it is perhaps more accurate than pheromone trap sampling. Its disadvantages are cost ($500+), access to electrical power and difficulty to maintain and check. Traps can get clogged with the many other insects attracted to the light. Separating out ECB moths can be challenging. Because of possible large insect numbers, samples can be very smelly, especially when wet, and difficult to sort. Traps need to be checked daily.

 Pheromone traps use a synthetic sex attractant that attracts male ECB moths. Two pheromone strains are available. For Nebraska ECB, the 'Iowa' strain of pheromone is used. Of several trap designs available, the best for ECB is the Heliothis trap (cost $50). The major advantage of pheromone traps is that only ECB moths are attracted and sorting of insects is not needed. Traps need to be checked regularly; three times a week is probably sufficient. The major disadvantage is that it only attracts the male moths and is not totally representative of moth activity. The traps have competition during the major moth activity period when the majority of females are also actively emitting their sex pheromone. Therefore, the peak pheromone trap catch tends to occur after this competition from real females is reduced. The result is that the peak catch in a pheromone trap can be delayed several days compared to the actual peak moth activity. To obtain pheromone sources and traps refer to ‘Sources of Pest Management Supplies’ (NF93-141).

 The major egg laying period for the ECB will begin when moths are most active (peak light trap catch) and continue for a period after peak activity (peak pheromone trap catch). The period of peak catch for these two trapping methods generally includes the major egg laying period of moths, up to three weeks.

NOTE: all insect trapping procedures are influenced by weather conditions, especially wind and temperature. Averaging multiple traps reduces this influence and is especially important with pheromone traps which are more influenced by local conditions.