Caterpillars of the
World - Singapore
Common Tit
Hypolycaena erylus
GODART, 1824
Family -
LYCAENIDAE
subfamily -
THECLINAE
Tribe -
HYPOLYCAENINI
introduction
|
habitats |
lifecycle |
adult
|
 |
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Hypolycaena erylus,
Singapore
( photo
courtesy Gan
Cheong Weei
©
2008 ) |
Introduction
The
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.
Habitats
This species occurs in many habitats including coastal mangrove,
lowland rainforest and temperate hill forest, at elevations
between sea level and about 1500 metres.
Lifecycle
The eggs of
Hypolycaena erylus are
laid on Meyna pubescens,
Vangueria spinosa ( Rubiaceae ),
Cinnamomum zeylanicum ( Lauraceae
), and probably on other plants.
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.
Adult
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
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