It is a curious quirk of the butterfly calendar that UK gardens are bare of butterflies at this time of year.
Every June we get calls from concerned BC members and journalists wondering what has happened to all the butterflies. The precise timing varies, depending on whether it is an early or late season, but the general pattern is so familiar that the butterfly recording community have christened it the ‘June Gap’.
So, what’s going on? The June Gap is simply a coincidence of the timing of butterfly life cycles in the UK. By June, many of the double-brooded (bivoltine) species that commonly frequent gardens have had their first emergence of the year and the adults have waned away. Their offspring are around, of course, but hidden away as eggs, caterpillars and pupae, and unseen by all but the most observant recorders.
So, the Brimstones, common whites, Holly Blues, Small Tortoiseshells, Peacocks and Commas that graced gardens during the spring are gone and the next wave won’t appear until July. Similarly, common single-brooded (univoltine) butterflies such as the Gatekeeper and Meadow Brown, together with less-frequent garden visitors such as the Marbled White and Ringlet, are yet to start their emergence, or in the case of the Orange-tip are over for another year.
The combined effect then, is of gardens that were busy with butterflies on warm days in late spring suddenly being empty of the colour, movement and joy that flying butterflies bring. Thankfully the effect is temporary, as the summer emergence of all the common ‘garden’ butterflies takes hold during July, but it can be disconcerting, even alarming to those caught unaware.
Escape from the dark days of the June Gap is possible though. There are plenty of other butterflies, ones that aren’t usually seen in gardens, on the wing at this time of year. Indeed, June is the main flight period for many of our most beautiful and threatened butterflies, including the Swallowtail, Black Hairstreak, Large Blue, Marsh Fritillary and Glanville Fritillary.
So hold your nerve, have faith and await the return of butterflies to your garden over the coming months – just in time, hopefully, for Big Butterfly Count.
Richard Fox
Surveys Manager
Follow me on Twitter: @RichardFoxBC