The first important step for a successful control of moths in greenhouse growing is the so called „monitoring“, the catching of the harmful moths with pheromone traps (or light traps) to determine the degree of infestation.
By means of species-specific pheromone traps that bear the attractant of virgin female moths in replaceable dispensers, it can be determined if and which moths are being active. As the traps do not catch female moths and only a part of the existing male moths, this is a mere measure to monitor the moth flight and to determine the dates of control. If male moths fly around, then the egg laying females are also around.
Distinguish the moths species with pheromone traps!
There are pheromones for many different harmful moths now that fly around in greenhouses. If a new pest appears that is difficult to identify, we would be pleased to assist you with the determination, as a successful control depends on it. The biology, development times and the knowledge about preferred host plants are important informations when deciding on the best control strategy.
The use of pheromone traps is easy to handle. The pheromone traps, usually they are so-called delta-traps, are simply opened to a roof, set up or hung and after equipping them with the pheromone bait they are ready for use. The attractant should be replaced regularly with a fresh dispenser. Per room only one trap should be used so that the moths can orientate themselves to the scent. If there are too many traps, this leads to a disorientation of the males, in the fragrance they cannot localize the trap anymore. The selection of the location of the trap is also important: Fresh air is often less disturbing than the windless corner in the greenhouse in which the pheromone-cloud stands still locally limited.
The right use of the trap is important because the activities of the pest should be evaluated. A wrong location or interfering pheromone dispenser may easily lead to misinterpretations and therefore also endanger the success of the Trichogramma use.
Control and document the catches of the traps!
The hung traps have to be controlled regularly to register the start of the moths flight – also „zero“ is important, the time before the moths flight starts. Trichogramma is an egg parasite and has to be released when the moths fly and lay their eggs.
It also makes sense to regularly record the catches of the trap in a data sheet or calendar in order to obtain a flight status. With the data it is possible to determine if the control has worked. Even after a control the traps should kept in use in order to detect a new infestation in time.
Combinable with the use of parasitic wasps
The pheromones last up to half a year, but can lose their full effectiveness, depending on environmental conditions, already before this. The attractants for moths are completely nontoxic and are also of no interest for the Trichogramma parasitic wasps. The parasitic wasps orientate themselves by the smell of the laid eggs and the traces that the female moths leave when landing and laying eggs.