Constantly appearing sand deposits in joints between paving stones are a source of concern for many home and garden owners. The lively, recurring phenomenon indicates animal activity. If flying insects swarm out of the areas, they are most likely digger wasps.
How to get rid of earth wasps in pavement?
Earth wasps in pavement, such as the common sand wasp or the gyro wasp, build their nests underground and can undermine the pavement. To remove them in the long term, the pavement should be opened, the sand base compacted and moist substrate added, as digging wasps prefer dry, sandy soil.
Wasps nesting under the pavement
Anyone who continuously observes sand gaps in one spot on the pavement of their driveway or courtyard is often dealing with ants. But these are easy to identify because of their busy crawling out and in. If this clear indication of the culprit is missing, it may be less conspicuous underground inhabitants. If you observe closely, you may be able to spot flying insects flying out and in - then the burrow under the pavement most likely belongs to a digger wasp colony.
Digging wasps belong to the group of wasps commonly referred to as earth wasps - because they build their nests underground. If you're unlucky, they'll also seek out the sandy ground beneath your pavement and dig numerous entrances to their breeding grounds. Digging wasps include, for example, the common sand wasp, the circular wasp and the bee wolf.
Nesting under the pavement can of course cause damage. Because the sand bed underneath is undermined and can therefore sink in places.
Interim balance sheet:
- Constant sand build-up in the joints between paving stones can indicate digging wasps
- Digging wasps include common sand wasp, gyro wasp, bee wolf
- Pavement undermining can lead to sagging
Long-term measures necessary
The problem with gyro wasps (which look very similar to bees) is their location loy alty. This means that they like to nest in the same location year after year, unlike other earth wasp species such as the hornet, the common or the German wasp. That's why it's not enough to just open the pavement in the fall, when the digging wasp nest is orphaned, and level the sand base again. It is best to strengthen and compact it with a little moist substrate, because digging wasps only like dry, sandy soil to nest in.
If you can somehow live with the digger wasps and perhaps a slightly crooked pavement in one place, you should do so. Even if digger wasps are not protected, combating them is not advisable given their beneficial properties and their contribution to the ecological balance in the garden.
