PLACEMENT OF PHEROMONE TRAPS WITHIN THE VEGETATION CANOPY TO ENHANCE CAPTURE OF MALE EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE)

European corn borer, Ostrinia nubilalis (Hubner), pheromone traps are typically placed in the open or above vegetation to monitor adult pres ence and abundance in areas where moths are likely to aggregate. After noting in another study that more moths were captured in traps overgr own with vegetation than in traps above it, replicated field experimen ts were conducted at 2 locations in Delaware to determine if placement of traps within the vegetation was more effective than traps placed a bove the canopy. At Newark, 3.83 times more males were captured in tra ps baited with Z-pheromone lure when traps were placed just below the canopy top in mixed weedy vegetation compared with traps 3 m away with the pheromone source 50 cm above the plant canopy. At Laurel in a mon oculture of developing wheat, 2.72 times more males were captured in t raps baited with E pheromone lure which were placed below the top of t he canopy versus trans above the canopy Greater variation in male moth captures was associated with greater diversity of the weedy sample lo cation relative to samples in wheat monoculture. Also, traps placed wi thin vegetation resulted in less variation in mean moth captures versu s traps placed above the canopy. This indicates that a better estimate of the population may be obtained by placing traps within vegetation. Results suggest that males are more likely to respond to calling fema les within the vegetation as opposed to above the canopy Placement of pheromone traps with the pheromone source below the top of the canopy appears to be critical for maximizing their effective capture of Europ ean corn borer male moths. We suggest that enhancement of pheromone lu res within vegetation may be caused by water vapor and volatiles assoc iated with plants.