Island populations are always vulnerable. As habitats shrink and populations become isolated they lose resilience. If you want to survive as a species then numbers and geographical reach are your friends.
The Norfolk and Suffolk Broads are home to a number of iconic species which have found a localised foothold in this watery corner of East Anglia. The outrageously lovely Swallowtail Butterfly (Papilio machaon) is probably the most recognisable. Britain’s largest butterfly with its black-veined yellow wings and blood-red spots at the base of its swallow tail it looks like a scrap of yellow handkerchief fluttering over the milk parsley. The Norfolk Hawker dragonfly (Aescha isosceles) can be found here too, patrolling the drainage ditches of the grazing marshes like a green-eyed wind-up toy. It shares some of these ditches with Britain’s largest spider, the Fen Raft Spider (Dolomedes plantarius) which has found a stronghold among the water soldier on Carlton Marshes.
But there is another species which has made its home here, less glamorous and less well-known, but no less remarkable. Galeruca laticolis is a small brown beetle barely a centimetre long – a beetle so unprepossessing no one has thought it necessary to give it a common name. To point to it you must still revert to Latin.
You can find maps of the range of most of these creatures in the handbooks. For the Swallowtail the area of cross-hatching covers the Norfolk and Suffolk Broads – though there are other isolated colonies on the Humber and the Isle of Wight. (As the climate warms the British sub-species of Swallowtail (britanicus) is threatened by the northward movement of its continental neighbour (gorganus). If, as seems inevitable, the two species meet and interbreed the unique form of britanicus will be lost.) The habitat cross-hatching for the Norfolk Hawker shares much of the territory with the Swallowtail, reaching down into the Suffolk broads. This species too is under threat, this time from loss of habitat as rising sea levels bring salt water incursions into the drainage ditches where it lives and breeds. The Fen Raft spider faces a similar threat.
However, you will search in vain for the cross-hatching that delineates the range of Galeruca laticollis. Because effectively this small brown beetle has no range. It is known at a single site in the United Kingdom, a small patch of protected fen and carr in the Yare Valley. You can walk the boundaries of Wheatfen in an hour. And while the beetle is here it would be wrong to say it was easy to find. It is confined not just to this single small site, but to a small area of this single site. It likes creeping thistle. So to locate it you have to seek out patches among the reeds and search the leaf axils.
To confirm your ID you could use this description found on the coleoptera.org website.
Pattern colour: none
Number of spots: none
Leg colour: black
It might charitably be described as unremarkable.
But the fact it is here at all is extraordinary. The whole of the Yare Valley is under threat from rising sea levels. It would take very little to upset the delicate ecological balance of the few square metres of marshland where Galeruca laticollis lives. An exceptionally high tide would probably do it.
We have grown used to the idea of ecological collapse, but all too often the narrative of melting ice caps, acidified oceans and disappearing rainforests operates on a scale that seems overwhelming. The precarious foothold of this little brown beetle has the power to turn a global issue into an intensely local one. Drill down into the existential crisis that threatens us all and one of the routes which opens up brings you to a small patch of creeping thistle at Wheatfen.