Caterpillars of the
World - Singapore
Family - LYCAENIDAE
subfamily - THECLINAE
Tribe - HYPOLYCAENINI
Hypolycaena species are collectively
known as Fairy Hairstreaks or Tits.
There are 45 members of the genus, of which 22 are found in Africa,
1 in China, 4 in Australia and 18 in the Oriental region.
Hypolycaena erylus is a common and
widespread species, found from Sikkim to Indo-China, and through the
archipelago to Papua New Guinea.
This species occurs in many habitats including
coastal mangrove, lowland rainforest and temperate hill forest, at
elevations between sea level and about 1500 metres.
The eggs of
Hypolycaena erylus are laid on
Vangueria spinosa ( Rubiaceae ),
Cinnamomum zeylanicum ( Lauraceae ), and probably on other
After hatching and
eating their egg shells the tiny larvae are abducted by weaver ants
Oecophylla smaragdina. The same species
of ant also captures larvae of Anthene emolus.
The ants carry their captives into their nests, which are
constructed by weaving leaves together.
Oecophylla are large and extremely aggressive ants, but they
make no attempt to attack the larvae, which probably placate their
captors either by using a chemical deterrent, or by means of an
"appeasement song" - research on various other Lycaenids has shown
that their larvae and pupae are able to stridulate or "chirp", and
that this sound deters ants from attacking.
The larvae feed
within the nests on leaves, and possibly also on substances
regurgitated by the ants. Studies have demonstrated that young 1st
instar emolus larvae ( and probably
also those of erylus ) are unable to
survive outside the ant nests, and will not feed on leaves outside
the nest. This could be due to the warm humid microclimate within
the ant nest, or due to a substance produced by the ants which
softens the leaves and makes it easier for the larvae to digest
them. After the larvae moult to the 2nd instar, the ants then remove
them from their nests, and carefully transport them to young sprigs
of the foodplant some distance away.
A few days later
when the larvae reach their 3rd instar they develop honey-producing
glands on their backs, and thereafter are constantly attended by the
ants, which "milk" them to drink the sugary secretion. The
relationship is not truly symbiotic, because while the larvae cannot
survive without the ants, the ants are able to obtain their "honey"
from other sources.
Males can commonly be found imbibing mineralised
moisture from sand, rocks, road surfaces or the outside walls of
buildings in forested areas.
Both sexes nectar
at various wild and cultivated flowers, always holding their wings
erect when feeding. They periodically oscillate their hindwings,
which causes the little tails to wiggle, and this, together with the
"false eye" marking at the edge of the wings diverts the attention
of predators away from the butterfly's head and body. Birds
generally try to predict which direction a butterfly will take, so
they aim their attack at a point just ahead of the butterfly.
Hypolycaena erylus and other Theclinae
turn this to their advantage, fooling the bird into aiming behind
the butterfly, which then flies forward and often escapes unharmed.
When not feeding,
both sexes sit on foliage, often high up on bushes or on the lower
branches of trees, but they also sometimes settle on low herbage and
bask with their wings fully outspread.
Hypolycaena erylus teatus,
Kuala Woh, West Malaysia