This makes it possible to kill and count the moths and determine species. Or, the moths may be kept alive and used for monitoring insecticide resistance levels. The lure used to bait the traps is a synthetic pheromone based on naturally occurring sex pheromones produced by the female to attract male moths during courtship. This bait, just like the sex pheromone produced by the female moth, dissipates in small quantities into the atmosphere. As such, wind speed and direction, ground cover, temperature, host plants in the area and other environmental factors affect the efficiency of the trap.
Temperature can also affect the efficiency of pheromone traps in several ways.
Bollworm and budworm moths are active at night, and night temperatures 55 F or lower during typical mating periods will inhibit moth activity. High daytime temperatures affect pheromone dissipation by causing rapid vaporization which leads to decreased attractancy at night. It is generally recommended that the pheromone tabs be changed every two weeks. However, in cases of extremely high temperatures, pheromone tabs may need to be replaced every 7 to 10 days. Other factors affecting pheromone trap effectiveness are moonlight and barometric pressure.