Pride of place among other invertebrate groups goes to the water bug Corixa iberica. Described as new to science as recently as the 1980s and still known only from a small scatter of localities along the Atlantic coastal fringe from Portugal to Shetland, it is abundant in all standing water on the isle. This relict species survives in places like Fair Isle because of its unpolluted waters coupled with reduced competition from more dominant sibling species and the general absence of predators.
Ward Hill rises to only 217 metres above sea level, but experiences some of the most extreme conditions in Britain, particularly on its northern flank. The area, where 14 obligate or facultative montane spider species bear witness to its highland characteristics, remains to be fully investigated.
Insect migrants are not restricted to butterflies and moths. There are frequent influxes of hoverflies, including Britain’s second record of Eupeodes lundbecki in 1982, and lacewings, beetles and bugs are turning up with increasing frequency. Indeed, Fair Isle may be well placed to register the impact of climate change on insect populations. The first-ever wasp, a drone of the Norwegian Wasp Dolichovespula norvegica, was found in 1991 and the previously unknown Sexton Beetle Necrophorus humator is now commonly seen at bird and mammal carcasses. In most years there is something unexpected and new, including a Birch Shieldbug in 2006 and two species of brown lacewing in 2008. A Migratory Locust Locusta migratoria was found by Deryk Shaw on 29 September 2015.
(Based on the ‘Fair Isle’ chapter by David Okill and Deryk Shaw in Bird Observatories of Britain and Ireland. Poyser, 2010).