Cherry fruit fly
The cherry fruit fly, Rhagoletis cerasi, is about 4 mm in size, has a yellow triangle on the back and pale yellow bands across the wings. They fly from mid- to late May and deposit eggs at a minimum temperature of 18°C, mostly in sweet cherries. The eggs are laid in the slightly colored cherries and not in the blossoms as is often thought.
Signs of damage
Externally, a small bore hole is visible which can be affected by fruit rot. The maggots are white and emerge from the cherries in June in order to pupate on the ground. They can ruin an entire harvest of cherries.
Pheromones
You only need two pheromones per season. The pheromone in the disc lasts for 6 weeks, which is plenty of time to cover the entire flight period of the cherry fruit fly. Hang sticky traps with a pheromone at the beginning of May in order to be sure to catch the beginning of the flight period. The flight period varies strongly according to temperature. In some years, we have seen the flight begin as late as the beginning of June. One pheromone disc is sufficient for several trees, if they are grouped together. If the trees are far apart, it's best to hang several pheromones. You generally only need to use one pheromone, even if you hang many sticky traps.
Sticky traps
The yellow sticky plate measure 25 x 40 cm and contain a non-drying glue on both sides of the plate. Hang 3 sticky plates per tree, with very large trees you may even hang 5 sticky plates. Especially the first year and with a high population pressure of cherry flies it is important to hang many sticky traps.
