THE AZURE BLUE BUTTERFLY. (Polyommatus Argiolus.)
([Plate XIII]. fig. 3, Male; 3 a, Female.)
Colouring:—Upper side, beautiful lilac blue—the male with a narrow black border (fig. 3), the female with a broad one, sometimes extending over the outer half of the wing (fig. 3 a). Under side, very delicate silvery blue, almost white, with numerous small black spots. No red spots.
Caterpillar, green, with darker line on back. Feeds on the flowers of holly, ivy, and buckthorn.
The butterfly appears in May, or sometimes in April, and again in August, frequenting woods and hedges, especially where holly and ivy abound. I noticed immense numbers about the ivied walls of Chepstow Castle.
As the name "Azure Blue" is in general use, I have retained it above, but that of "Holly Blue," sometimes
applied to it, is preferable, as its colour is much less an azure blue than that of Adonis.
Localities:—Common in the south, and found as far north as Durham and the Lake District. Not known in Scotland.