Fooling with Pheromones–or Moths Keep Following Me Home
Most orchards must deal with two serious insect offenders, the Oriental Fruit Moth and the Codling Moth. They can have multiple generations every summer, and each fertile female lays approximately 100 eggs per generation. That’s a lot of worm damage. Neither of these moths is native to the United States, nor do they have any “natural” enemies to reduce their numbers. As a preventive measure, we use pheromone disruption in early spring to confuse male moths so they do not mate. Suspended from fruit trees in a pattern particular to our orchard, pheromone laden wire ties saturate the atmosphere with the scent of female moths. In turn, the smell disrupts mating, averting egg and worm damage in our apples and peaches. Worth the extra expense, this organic strategy helps us eliminate several insecticide applications annually.
Because of its effectiveness, pheromone disruption has been part of our IPM program for many years, but it is not foolproof. To ensure Oriental Fruit and Codling Moths stay within a manageable range, we routinely scout (our daily dog walks), monitoring for pests and pest damage. This is also a good time to check our moth traps. Concurrent with mating disruption, we hang traps containing pheromone lures that attract male Oriental Fruit and Codling Moths. If we catch more than five per trap per generation, we exceed the minimum damage threshold, prompting us to determine our best control measure. Codling Moth Granulosis Virus is an organic material that we apply sparingly when necessary, and it specifically targets Oriental Fruit and Codling Moths, allowing beneficial insects to progress unharmed. To synchronize this control, we first must establish the number of days until egg hatch (a time period determined by a degree day temperature model).
Almost invariably, pheromone disruption arrests any need for further action against the moths. We choose instead to monitor traps and accept some damage rather than to depend on a calendar based spray schedule that may stamp out all insects–the good, the bad, and the ugly.