Phased Dike Mowing Extends Insect Season While Safeguarding Flood Protection

Across the Netherlands, local governments are shifting to a phased method of dike upkeep, cutting the grass on the slopes in sections instead of removing it in a single sweep. This strategy aims to lengthen the period during which insects can feed on the plants, yet it continues to satisfy the flood‑defence safety standards.

Ecologist Constant Swinkels from Radboud University noted that routine mowing is still essential for keeping dikes stable. He warned, "If you don't mow, trees or sturdy shrubs…" may become established, which could weaken the earthwork’s structural soundness. Keeping vegetation low curtails the development of deep roots that might destabilise the dike, yet it preserves isolated taller patches that serve pollinators and other insects.

This phased cutting produces a patchwork of habitats throughout the dike corridors. Certain stretches are mowed early in the year, letting the untouched strips bloom later and supply nectar and pollen after other parts have already been trimmed. Such a mosaic supports diverse insects—including bees, butterflies and beetles—that are facing population drops across Europe because of habitat loss.

Regional water boards are now embedding these ecological factors into their regular inspection timetables. By scheduling mowing teams to tackle alternating segments, they preserve the necessary slope and drainage of the dikes while extending the period that insects have access to food. This tactic is consistent with wider European Union biodiversity policies that promote nature‑positive actions within infrastructure maintenance.

Although the method is attracting interest, specialists warn that it requires close oversight. Excessively thick growth may still endanger the dikes, especially if invasive plants become established. Continuous monitoring will juxtapose dike condition data with insect surveys to verify that safety and ecological objectives stay in balance. Should it prove effective, the approach could become a template for nations aiming to harmonise flood protection with biodiversity preservation.