A SURVEYOR from the Northern Ireland Environment Agency has discovered a rare butterfly previously thought to be extinct.

While working in Co Fermanagh, NIEA's Bobbie Hamill came across the Small Blue Butterfly – Cupido minimus – which was last recorded on its only known NI site in 2001. Although the species can be found in other parts of the UK and Ireland, it is undergoing a significant decline.

NIEA’s Habitat Survey Team recorded a total of seven butterflies on the wing on May 31. They partially attribute the occurrence of the species in relatively high numbers to the unusually warm weather – Northern Ireland has enjoyed its warmest spring since records began.

Ms Hamill spotted the butterfly while assessing the condition of the flower-rich plant communities in one of NI’s most important grassland Areas of Special Scientific Interest, just west of Derrygonnelly. An assessment of these special areas is undertaken by NIEA every six years to ensure that their scientific interest is being maintained.

She said: “Not only is the Small Blue our smallest butterfly, but unlike other members of its family it is inconspicuous and can easily be overlooked. Rather than blue, the upper wing is actually dull brown in colour, fringed by white hairs with a dusting of blue scales at their base and the underside is silver blue with dark speckles. In addition, at little more than 20mm, it is not surprising that these beautiful little butterflies are difficult to spot.

“We would especially like to commend the landowners and managers in the area for continuing to graze these special sites in a sustainable manner, creating the ideal conditions for plants to flourish and the Small Blue and other important invertebrates to breed. It is still possible that other colonies of this tiny butterfly are surviving in suitable quiet corners of Fermanagh and beyond, so be on the lookout.”

Catherine Bertrand, head of conservation for Butterfly Conservation in Northern Ireland, said: “I cannot articulate how delighted we are that the Small Blue has been reconfirmed. Our volunteers have revisited the site sporadically over the past 16 years since the butterfly was last seen, with no success. We genuinely believed it was extinct from Northern Ireland.”

She said that Butterfly Conservation had followed up NIEA’s discovery with a further visit to the site, specifically to survey the extent of Kidney Vetch, the caterpillar's sole food plant, and to hunt for Small Blue eggs laid on the flower heads.

She added: “The outlook for the Small Blue is currently very positive, with plenty of the food plant across the site, lots of eggs for the coming season and most importantly, a landowner who is working to ensure this remains one of the most important wildlife sites in the country."