 The archipelago 's isolation has resulted in a lack of biodiversity . The most successful colonists with nearly two hundred species are the flies followed by beetles with approximately 140 species . There are no bees on the islands so the flies are probably important pollinators of plants . One beetle , the rare and endangered weevil , Ceutorhynchus insularis , is known from only Dùn and the Westmann Islands , an archipelago off the south @-@ west coast of Iceland . Less than one hundred species of butterfly and moth occur , compared to 367 recorded on the Western Isles . Red admiral ( Vanessa atalanta ) and painted lady ( Vanessa cardui ) are two of only seven species of butterflies , both well known and common migrants . Common summer moths are the antler ( Cerapteryx graminis ) , dark arches ( Apamea monoglypha ) and the migrant silver Y ( Autographa gamma ) . One unusual moth recorded is the least carpet ( Idaea rusticata ) , an occasional migrant , and in the UK , usually recorded in the south @-@ east of England . On 4 September 2014 a rare vagrant oleander hawk @-@ moth ( Daphnis nerii ) was recorded . Oleander is not found in the UK every year , and the larva have never been recorded in the Britain . 
