Full article from edition 5.
Singing The Blues
By Kirsten Light, Rights of Way and SSSI Ranger at
The male Adonis Blue butterfly, Lysandra bellargus, certainly lives up to its name; it is indeed ‘handsome’. It never fails to impress, fluttering by in all its iridescent electric-blue finery. The female is generally brown in colour with a shimmer of violet-blue. This beautiful creature’s stronghold is on our doorstep in Dorset and is restricted to warm, south-facing chalk downland slopes with short turf. It’s hard to imagine it being so rare nationally as it appears locally in abundance.
The best places to see this blue beauty on the Lulworth Estate are on Bindon Hill in West Lulworth and at the Five Marys in East Chaldon. Here you can watch them hovering above the Horseshoe Vetch on which they lay their eggs. This is the only plant that the hatched caterpillars will eat. We have two opportunities to observe Adonis Blues because they have two broods each year, the first adults emerging in late May / beginning of June and the second in late August / beginning of September – when most other butterfly species are looking tattered and at the end of their short lives.
Aiding the Adonis Blue with its niche requirements are ants, particularly the Red Myrmica sabuleti and Black Lasius alienus Ants as these are the most common species on their breeding ground. These ants are, however, only common if the ground is warm and the turf well-grazed.
The relationship is symbiotic: the vulnerable caterpillar is protected from other carnivorous ants, parasitic wasps and pathogens by guarding the ants – which, in turn, feed on nutritious droplets of honey exuded from the caterpillar’s skin. After a day’s feeding, the ants follow the caterpillar underground and tuck it into a cell made of loose earth which provides protection for the night. The chrysalis stage of the lifecycle also receives the ants’ undivided attention leading up to actual emergence: when it finally breaks free of its pupal case, an audience of ‘soldiers’ stands to attention until the butterfly spreads its wings for the first time.
So where does the honey-reward come from? This protection is paid for with honey produced in three ways: by a honey-gland, through pores and through tentacles. If this isn’t extraordinary enough, it has since been discovered that the caterpillar of this species ‘sings’ as it crawls, rubbing two tentacles behind its head. This ‘singing’ is not at a pitch that we can detect but appears to arouse the ants: something for further research.
So, a relationship made in heaven. It’s thought unlikely that the Adonis Blue would survive without this protective military operation, so perhaps we should therefore hold ants in higher esteem. Research has shown that, given the right conditions, there is approximately one ants’ nest every 1m², so the next time you’re bitten by one of these creatures as you park yourself on a grassy slope to watch the Blues, perhaps be minded to think a little more kindly of them.