Black hairstreak forewings. The most conclusive way to distinguish the two is by the row of black spots accompanying the orange band which the white-letter hairstreak never has. They spend most of their lives in the canopy or in dense scrub, feeding on honeydew, and very rarely come down to ground level. Eggs are laid singly on young blackthorn "Prunus spinosa" growth and it is this stage which hibernates. Although blackthorn is the main foodplant, wild plum "Prunus domestica" and other "Prunus" spp are occasionally used. The caterpillar hatches the following spring, at the end of April, just before the buds open
Prunus avium parent species of "Prunus cerasus" (sour cherry), by way of ancient crosses between it and "Prunus fruticosa" (dwarf cherry) in the areas where the two species overlap. All three species can breed with one another. "Prunus cerasus" is now a species in its own right, having developed beyond a hybrid and stabilised. Pliny distinguishes between "Prunus", the plum fruit, and "Cerasus", the cherry fruit. Already in Pliny quite a number of cultivars are cited, some possibly species or varieties, Aproniana, Lutatia, Caeciliana, and so on. Pliny grades them by flavour, including dulcis ("sweet") and acer ("sharp"). and goes so far