The Large Blue butterfly, however, is less symbiotic, exhibiting a form of parasitism of a specific species of the Myrmica ant. The caterpillars, being similar to Myrmica ants physically and chemically and possibly using other forms of mimicry, trick the ants into taking them back to the ant nest, where they either become a predator of the ants larvae or beg for food by acting like an ant larvae in what is known as a “cuckoo” strategy
Holly Blue (Celastrina argiolus)
Family: Lycaenidae
Subfamily: Polyommatinae
Tribe: Polyommatini
Genus: Celastrina
Species: argiolus
Subspecies: britanna
Key ID Features:
Lilac-blue wings of male have thin black borders, thickening toward the tip of the forewings, with chequered white fringes.
Lilac female upperside has broad, black bands on fore and hind wings.
Both sexes have silvery-blue underside, finely speckled with black but no trace of orange.
Seen in UK: April-September
The Holly Blue is primarily found in the southern half of the British Isles, and is a frequent visitor to gardens. This species is renowned for fluctuating wildly in numbers, forming a predictable cycle over a few years, believed to be caused by parasitism from the wasp Listrodomus nycthemerus whose sole host is the Holly Blue. The wasp lays its eggs in Holly Blue larvae, with a single adult wasp eventually emerging from the Holly Blue pupa. In England and Wales this species is widespread and common, south of a line running from Cumberland in the west to County Durham in the east. This species is also found on the Isle of Man and throughout Ireland, but is absent from Scotland except as a scarce vagrant.
Text (c) UK Butterflies, used with permission
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Photographer: Tim Tapley
