Not the beetle itself, but the larvae — grubs — eat at the roots of young plants and cause growth to slow down or fail. Chemical plant protection products are restricted against this pest, and their use is increasingly being restricted. By covering the ground with fine-mesh insect netting during the mating period of the cockchafer, the beetles are prevented from burrowing in to lay eggs. The success of keeping off the cockchafer depends on the right time to cover it up.
The cockchafer emerges in the spring. First, it feeds on tree leaves — this is called “flying out”. After ten to fifteen days, the females are sexually mature. After mating, they fly back to the plot to lay eggs in the ground. This usually happens around May and June.
An advantage of covering is that the insect screen only has to stay in place for a few weeks. The cockchafer lives for a short time and lays its eggs within a few weeks. It is crucial to apply the mesh approximately seven days after the start of fledging — i.e. before mating and flying back. Using light traps and pheromone traps around the plot, you can accurately estimate when the activity starts.
The mesh can be removed a few weeks after the peak of the mating period — usually two weeks after the return flight. This is deliberately a few weeks and not earlier, because most of the beetles die after laying the eggs, but a small part still has a second egg. As a rule, you should wait until at least 2 weeks after the end of the return flight before removing the insect screen.
The success of keeping off the cockchafer depends on the right time to cover with insect screen. When the plot is covered too early, the cockchafers crawl out of the ground and cannot fly out. When this happens, they lay eggs under the insect screen out of need, this is not desirable.
If they cover too late, the cockchafers are already back to the breeding site to lay eggs and many eggs will hatch. This results in a lot of creeps and ultimately a lot of damage to the crops.
Not only the mesh size is important — also the stiffness of the wire. If it's too smooth, beetles can wriggle their way through. Ornata Plus 95135 meets all these requirements.
A trial is currently being carried out in a walnut orchard with Ornata Plus 95135
