Country diary: A great pretender lurking on the riverbank

With his warning colours and a wingspan of 30mm, the plumehorn is impressive, but he’s not the most captivating pretender on the riverbank. Lurking in the long grass, I spot a bulbous yellow abdomen with black scalloped banding, then another – and 16 striped legs. They belong to a couple of female wasp spiders (Argiope bruennichi), another species that mimics wasps to protect itself from predation and which was first recorded in Hertfordshire in 2005. Wasp spiders mainly prey on grasshoppers, but – despite several prospective victims in the vicinity – these two are catching pollinators. Three inert parcels already dangle from their orb webs. One looks to be a wasp and, as I watch, a black muscid fly blunders into the sticky silk and is swiftly encased.