Butterflies of Britain
Family - LYCAENIDAE
Lysandra bellargus, male, Hod Hill,
Adonis Blue is found throughout most of the warmer parts of Europe,
but is absent from Norway, Sweden, Finland, the Mediterranean islands,
and all except the southern counties of Britain. Beyond Europe it also
occurs in Turkey, and eastward to the Black Sea.
continental Europe it is possible to confuse this species with several
others in the same genus. All members of the genus
Lysandra are characterised by having
chequered margins, which are not present in
Agrodiaetus etc. The other members of
Lysandra have a much paler silvery blue
colouration, with the exception of the Spotted Adonis Blue
L. punctifera, which has a series of
sub-marginal black spots on the upperside wings.
Lysandra bellargus, male, Martin Down,
Adonis Blue, like most other "Blues" is sexually dimorphic - only
the males have the beautiful overall electric blue colouration. In a
photograph it is impossible to convey the brilliance of the blue,
which glints in the sunshine and changes hue according to the angle
by comparison are dark chocolate brown, with a dusting of deep blue
scales across the basal and median areas of the wings. The extent of
the blue dusting varies considerably between individuals of the same
population. All females also have a dark discal spot on the
forewings, and a row of orange sub-marginal lunules on the
hindwings. The female Chalkhill Blue is very similar, but slightly
larger and with a dull earthy brown ground colour. It also has
suffused whitish edging to the black sub-marginal spots on the
upperside, as compared to blue edging in
The Adonis Blue and many other species
have conspicuously coloured
males, but relatively plain females.
Males use "flash colouration" to confuse
predators. If a bird sees the butterfly in flight or basking
on a flower, it targets the bright blue image. The butterfly
reacts to threat by settling immediately on the ground and
closing it's wings, revealing the spotted greyish underside
which is an effective camouflage when it is settled on chalky
are surreptitious, tending to move very little until
mated. When searching for egg-laying
sites they tend to move slowly and deliberately, and for them,
are a better means of defence. Most
female Adonis Blues are dingy brown in colour, with hardly any
blue scales, so they easily escape the notice of birds. The
female illustrated below is an exceptionally bright form, but
still far less conspicuous than the bright blue males.
Adonis Blues sometimes hybridise
with the Chalkhill Blue
producing the hybrid
but the progeny are infertile.
In Britain the butterfly is confined to dry chalk and limestone
grasslands in the counties of Dorset, Somerset, Wiltshire,
Hampshire, the Isle of Wight, Surrey, West Sussex and Kent.
It breeds in compact and
dense populations comprising hundreds, or sometimes many thousands
of individuals. The populations however are extremely localised -
breeding in a restricted area of each site, even if the larval
foodplant is widespread. Furthermore movement of adults between
nearby sites is extremely unusual - the butterflies seem to find
barriers such as roads, cultivated fields or tall hedges virtually
Most colonies are on
south-facing slopes where horseshoe vetch grows in profusion, and
which are heavily grazed, producing a short sward pock-marked with
little patches of bare ground such as those caused by erosion,
cattle poaching or rabbit excavations. A very warm microclimate is
essential, as even a minor relaxation in grazing can bring about a
major decline or local extinction. Many colonies are restricted to
very localised areas within their sites, e.g. along the south facing
ramparts of ancient hill forts, or the west facing bank of a dyke.
In Europe the butterfly
is far less fussy about it's habitats, and can be found flying along
roadsides, or in areas of long grass and scrub on limestone
Lysandra bellargus, female, Ballard
Down, Dorset ©
There are two generations in Britain, the first emerging in May, and
the second in late August.
The flat whitish eggs are laid on the underside
of terminal leaflets of horseshoe vetch
Hippocrepis comosa. There are no alternative foodplants. The
butterflies choose plants which are in full sunlight, in sun-baked
positions at the edge of rabbit scrapes, paths or other patches of
bare ground. The eggs are laid singly, but often several females
will visit a particular favoured plant, and consequently as many as
30 can be found in very close proximity.
The larvae feed diurnally. When tiny they feed on
the under surface of the leaves where they nibble here and there,
producing tiny holes, but leaving the upper cuticle intact. The
feeding damage can be seen from above as a peppering of microscopic
shiny spots. When older the larvae rest on the upper surface of the
leaves but are very well camouflaged and difficult to spot.
They are commonly attended by ants
Lasius alienus or Myrmica sabuleti.
The ants are attracted by a sugary secretion which they milk from a
gland near the caterpillar's tail. The larvae seem unable to survive
without the ants, whose presence deters other insects that would
otherwise attack and kill them.
At dusk the larvae
retreat to the base of the foodplants, where they assemble in groups
of about half a dozen. They are followed by the ants which cover
them in a thin layer of soil particles, and stand guard over them
during the night.
Adonis Blue larvae ( and those of most other
Blues ) appease their attendant ants by "singing" to them, thereby
avoiding being eaten themselves. It is not known how the larvae
produce their song, although there are microscopic knobs and plates
around the opening of the honey gland which may be involved.
Larvae of the second generation enter hibernation almost immediately
after hatching, and awaken to begin feeding in March.
fully grown they are deep green, each segment having a prominent
hump. A series of bright yellow dashes runs along each side below
the spiracles, and a pair of broken yellow stripes run along the
pupa at first is pale olive, but changes to become straw coloured
after a few days. It is formed in crevices on the ground, but ants
quickly cover it with a thin layer of soil. Sometimes pupae have
been found inside the brood chambers of ants. Immediately prior to
emerging from the pupal case, the butterfly produces a crackling
song to pacify the ants. It then rapidly breaks through the soil to
crawl up a stem where it hangs to dry it's wings.
Lysandra bellargus, male, Hod Hill,
almost incessantly back and forth across their habitat, fluttering
just above the sward in a constant search for females. Periodically
however they need to refuel, and stop for a minute or two to nectar
at the flowers of horseshoe vetch, bird's foot trefoil, marjoram,
hawkbit or thyme. Occasionally they visit taller plants including
thistles, knapweeds and hemp agrimony. They have also been
frequently observed gathering to feed at animal droppings.
Lysandra bellargus, male, Cissbury
Ring, West Sussex ©
seen far less frequently as they are much less conspicuous, and are
usually mated before taking their maiden flight.
without preliminary courtship, at about midday. Copulated pairs, if
disturbed will fly a short distance to find a safer resting place.
Lysandra bellargus, male, Hod Hill,
In hazy sunshine,
butterflies of both sexes, including copulated pairs, will bask in
rabbit scrapes or other bare patches, with their wings held partly
or fully open.
On sunny days, as dusk
approaches, the butterflies congregate to roost on grass-heads in
sheltered areas where tall grasses receive the final rays of the
setting sun. They roost head-downwards, often in groups of 20 or 30,
with up to 5 individuals on each grass-head.
Lysandra bellargus, copulated pair,
Old Winchester Hill, Hampshire ©