Author: Michael Blencowe.
I struck lucky with the weather (yet again!) for my wildlife walk at Iping Common and, as we stood in the nature reserve's car park I found myself recommending sun-tan lotion as opposed to waterproofs. The sandy, sun-baked heaths of West Sussex are hot, dry habitats and for the wildlife that lives here they can be very hostile places. Some of the heathland plants have some extreme adaptations to these conditions but it's the insect inhabitants that fascinate me. In order to survive many species of insects undertake some devious and frankly villainous behaviour.
One of our targets for the day was the silver-studded blue - one of the UK's rarest butterflies and one which is confined to only a few heathland sites in Sussex. The gorgeous male butterflies were seen in good numbers throughout today's walk and the group were able to get close to the blue male and brown female butterflies to see the shining 'studs' on the underside of their wings (photo of female, below).
The group was also stopped in their tracks by a heathland moth - the clouded buff. It's a rather dull name for what must be one of Britain's most colourful moth species with yellows outlines in pink. The caterpillars of moths and butterflies on the southern heathlands are prey for solitary wasps that make their nest burrows in the sandy soils. Species such as Ammophila pubescens can be found on Iping Common and these wasps lay their eggs in their nest burrows and head out across the heather to find their caterpillar prey. The prey is paralysed and then carried back to the wasp's lair where it is fed to the wasp larvae within - the entrance hole being covered up again while the wasp hunts for food for her other offspring. But on heathlands even the hunters have to watch their back. Lurking in the shadows is the mottled bee-fly. This fly is a parasite and the wasp's nemesis. The bee-fly lays its eggs near to the wasp's nest hole and its larvae hatch out... and wait. When the wasp unearths her nest hole it has to drop the caterpillar. It's then that the fly's larvae climb on to the caterpillar and, in a Trojan Horse scenario, are carried into the wasp's lair. Once inside they can feed on the wasp larvae and caterpillar food being provided by the adult wasp. It's all rather sinister but I find the interactions between prey, predators and parasites endlessly fascinating. There were large numbers of the fly and its host seen on the walk today (both of which are nationally rare species) and Mike Davis, with a bit of patience, managed to obtain a great photo.
Other highlights today included a fly-past by one of the greatest heathland hunters - the hobby. The fact that it flew overhead right on-cue as I was talking about it led to a few accusations that I had trained the bird. Thanks to everyone who joined me on the walk.