When I first moved to Dorset, I was pleased to discover Holly Blues in my garden. There are two broods. The first brood flies from mid April to the start of June & the second brood from mid July to the end of August. The main attraction in my garden is the significant amounts of Ivy. This is an easy to identify Blue with this distinctive pale-blue underwing pattern. It is larger than the only species with a similar underwing pattern: the Small Blue. But Small Blues are typically a species of coastal grassland, whereas Holly Blues are found in a variety of habitats. A pale blue fluttering high in trees & bushes is most likely to be a Holly Blue.