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Rare UK beetle discovery in Castle Hill Local Nature Reserve

Striped summer chaffer

This month it has been confirmed that a beetle, that was previously unknown in the UK outside of the Channel Islands, is alive and thriving in Newhaven, East Sussex.

The beetle, Rhizotrogus aestivus, or the Striped Summer Chafer, is similar in appearance to other familiar beetles including the Cockchafer and Summer Chafer, but it is smaller and less hairy. Like many other chafer species, it feeds as a larva on the roots of plants.

The discovery was made following the identification by Steven Teale, Specialist Adviser at Lewes District Council, of a beetle photographed at the end of April last year by Sue Cross, a member of the Friends of Castle Hill Local Nature Reserve in Newhaven.

Adults of the Striped Summer Chafer appear slightly earlier in the year than other closely related species, from April until June.

The adults emerge shortly after sunset each night and are active for only about 25 minutes before settling down again. During this short time the males search for females, which perch low down on grass stems and appear to produce pheromones to attract the males.

Steven Teale said: "Although the chafer is much less clumsy than Cockchafers and Summer Chafers, it is still quite clumsy and can take some time to home in on a female.

"Clusters of several amorous males can be found clambering over a female and, where more than one female is in the same patch of ground, up to several dozen males have been found in a scrum around them."

The discovery of this species, which has grown into a large colony at Newhaven, is remarkable for a few reasons.

Steven said: "It is rare for a large, conspicuous and charismatic beetle to have been overlooked until now. It is probable that it hitched a lift, possibly on more than one occasion, on a boat across the English Channel rather than making the journey on its own. Its bulk, relatively poor navigational skills and the fact that it is active for less than half an hour at night make a journey under its own steam unlikely."

This method of introduction is not uncommon; newly colonising species are often first recorded around ports such as Newhaven and other very special species including moths and beetles have been found at Castle Hill regularly over the years.

The astonishing thing about this previously unknown beetle is that members from the Friends of Castle Hill LNR, led by David Harris and Steven Teale, have found it in its thousands on grassland between Cliff Road in Peacehaven to the west and Poverty Bottom near Denton in the east. This area covers 24 square miles.

This suggests it colonised the area around Newhaven some years ago. David and Steven are making further searches this year, while observing the Covid-19 distancing measures, so it might be found to be even more widespread than we already know.

The discovery of the beetle is a testament to the enthusiasm and effort of the team at LDC's Castle Hill Reserve and a great success story for one of Newhaven's finest open spaces.

Photograph courtesy of Peter Varnham, Castle Hill Local Nature Reserve member