Adonis and Horseshoe Vetch

Adonis Blue, Lysandra bellargus, male

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I made a dash to Mill Hill this morning to do this week’s butterfly transect before the clouds rolled in. There was a strong wind and 50% cloud cover so I didn't see any till I arrived at the bottom of the hill where I recorded several Dingy Skippers, an Adonis Blue and a Small Heath. The hill is now covered in yellow Horseshoe Vetch, which is the food plant of the Adonis Blue. 

Horseshoe Vetch, Hippocrepis comosa on Mill Hill

This butterfly almost disappeared after rabbits were decimated by myxomatosis. This was because rabbits keep the swards of vetch at the right height for the larvae to survive. Tall swards mean that the temperature at the base is too low for the caterpillars. Like other blues, the Adonis has a close relationship with ants which are induced into looking after them from the first moult of the larva to emergence from the pupa.  Key elements in the lava’s armoury are honeydew and scents. The Adonis Blue  is found on chalk downland in southern England, usually south facing like Mill Hill.

Adonis Blue, Lysandra bellargus, male

Horseshoe Vetch, Hippocrepis comosa

Horseshoe Vetch, Hippocrepis comosa