Bee-flies (Bombylius major) were out and about on my allotment at the weekend. They parasitise solitary mining bees as they lay their eggs in the bee nests, the fly larva then eats the pollen store intended for the bee larva, followed by the bee larva itself. Bee-flies don’t have a negative impact on solitary bee populations, a healthy bee-fly population indicates a healthy solitary mining bee population, it is all part of a healthy ecosystem.