Berry sawfly (Nematus ribesii) is a permanent problem in organic (goose) berry growers. The greedy larvae (bastard caterpillar) can eat all leaves in a very short period of time. As a result, the plant weakens and production loss can occur. Berry sawfly overwinters as a larva in a cocoon in the ground and starts its flight in March. During April and May, the larvae can eat on the leaves, after which they pupate back into the ground. The 2nd generation can again cause a lot of damage in the summer months. Current control is done by manually pinching the larvae (time-consuming and not efficient) or an (emergency) treatment with spinosad against leaf-eating sawfly larvae/caterpillars (harmful for beneficials). Side effects of bitter salt applications as a leaf fertilizer (hardening of the leaf) are not always efficient because the larvae are already too large. A sustainable strategy is needed.