Tim writes: this is Britain’s smallest butterfly, the Small Blue, which is about the size of the nail on my little finger. In Britain their only larval foodplant is Kidney Vetch (Anthyllis vulneraria) but they only feed on the flowerheads. The female carefully selects a flower head of kidney vetch, tasting with her feet and antennae that it is the right species. Then she dips her abdomen into the flower to lay a single egg on one of the florets. The newly hatched caterpillar will eat a hole in the calyx then will venture inside to feed on the flower parts and developing seed. Small Blue caterpillars are cannibalistic so the female must check a flower head very carefully to make sure there isn’t already an egg there. Because an earlier-laid egg would hatch first so would be bigger and more likely to be the eater than the eaten. They sometimes pupate in the flower head but more usually low down in surrounding vegetation.
Its scientific name Cupido minimus is after Cupid, the Roman god of love (Eros is the Greek equivalent). Minimus simply means the smallest as it was the smallest butterfly known to science when it was named in 1775 by Swiss entomologist Johann Kaspar Füssli, when he was just thirty years old.
