Life cycle

Horse-flies lay their eggs on the plants that grow in damp places. When the larvae hatch, they crawl down into the moist earth or into the water where they live as voracious predators of the prey they can overpower.

The adult horse-flies are active and fast fliers, and they can fly far away from their breeding site. They are common in the high summer, and statistics from the Danish National Pest Control Laboratory show that 70% of all horse-fly encounters take place in July, the other in June and August.