The number of butterflies on a buddleia bush is our best informal measurement of a butterfly summer.

Buddleias may be non-native – and one of the “weeds” disparaged by the Daily Mail this month for disfiguring Brighton – but the extravagantly scented purple tubes are a rich source of late-summer nectar when other blooms are relatively scarce. Colourful garden nymphalids – small tortoiseshells, peacocks, red admirals, commas – must fuel up because they hibernate as adult butterflies; they’re joined by the painted lady, mustering the energy to migrate to sunnier climes.

Like most enthusiasts, I’ve been dismayed by the relative absence of buddleia butterflies in the 21st century compared with the gatherings in the 1980s. I’ve only got seven summers of data for the 21 buddleias in my current Norfolk garden (all from cuttings – you don’t ever need to buy a buddleia) and 2019 was decent but this year, despite grotty weather, is the best.

Thirteen peacocks graced a single buddleia earlier this month. This week it’s the turn of red admirals, with 14 on one shrub. In Devon, my dad has counted 40 butterflies on his buddleia.

Buddleias were savaged by spring frosts, so perhaps later flowering has helped. This summer may also be proving better for butterflies than I dared hope.