The late summer blues
In recent weeks, we have had the second brood of a very special butterfly, the ‘holly blue’. The underwing of this tiny but stunning butterfly is silvery white and very distinctive in flight.
Holly blues associate with their larval food-plants, mainly holly, ivy, and shrubs like berberis.
This means their main habitats include woodland edges, overgrown hedges, and gardens.
In this respect, they differ from their widespread cousin the ‘common blue’, a denizen of short-turf grasslands with their food-plant the yellow bird’sfoot trefoil (a member of the pea family).
Rarely found in gardens, common blues tend not to venture far from their main habitats.
This is unlike the holly blue, which is a frequent visitor; meaning that should you spot a ‘blue’ butterfly away from grassland it is most likely to be holly blue.
Furthermore, at this time of year it will be an adult hatching out as a second brood.
The holly blue varies from years when it is very abundant to other times when it is quite scarce.
This pattern is because of a tiny parasitic wasp that preys on the caterpillars and which follows the blue population increases but then causes them to crash.
● Professor Ian D.
Rotherham, researcher, writer & broadcaster on wildlife & environmental issues, is contactable on ianonthewildside@ukeconet. org; follow Ian’s blog (https:// ianswalkonthewildside. wordpress.com/) and Twitter @
IanThewildside