Life Trockenrasen: Bembix rostrata

The genus Bembix is highly diverse, with over 340 species worldwide. However, only one species, Bembix rostrata, is found in Germany. It inhabits primarily dry, warm, open, and sandy habitats such as dunes, quarries, and extensively managed meadows. 

Legs as Excavation Tools

With its distinct black-and-yellow striped abdomen, the Bembix rostrata is one of the more striking members of the Crabronidae family. It has large green eyes and long, slender legs, which are not only suited for quick movement but also act as shovels for digging nests.

Intricate Parental Care

Bembix rostrata constructs a nest by digging a 10 to 15 centimetre deep burrow in loose sandy soil. As it spins rapidly around its axis during excavation, it produces a buzzing sound. Once the burrow is ready, the wasp places a fly inside and lays an egg on it. The fly serves as food for the freshly hatched larva. The female Bembix rostrata is highly diligent, continually providing her larva with paralyzed flies. In peak summer, she delivers around 50 flies to a single nest. After each feeding, the nest is carefully sealed again. Once the larva pupates, the wasp digs a new burrow to raise another larva. Due to this labour-intensive process, a single female can rear only six to eight offspring per summer.

Conservation

Bembix rostrata plays a vital role in ecosystems and agriculture. It acts as both a natural predator of pest insects and an important pollinator. These wasps are highly site-loyal, using the same nesting locations for extended periods. However, the loss of open sandy areas due to human activity poses a significant threat to their habitats. Preserving dry grasslands, sand dunes, gravel pits, and other open areas is essential to protect existing nests and create nesting opportunities for new populations.