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Butterflies of
the Amazon and Andes
Giant Glasswing
Methona confusa
BUTLER, 1873
Family - NYMPHALIDAE
subfamily - DANAINAE
Tribe - ITHOMIINI
subtribe -
MECHANITINA
Methona confusa male, Madre de
Dios, Peru ©
Adrian Hoskins
Introduction
The Ithomiini comprises of 376 known species, although it is
likely that at least another 30 will be discovered in the near
future. All are confined
to the neotropical region.
Ithomiines
are unpalatable to birds, and are consequently mimicked in
appearance by many other species. These include other unpalatable
species ( Müllerian mimics ), not only from the Ithomiinae but
also from several other butterfly families. There are also a large
number of edible species ( Batesian mimics ) which have evolved
similar patterns. Birds have the ability to memorise butterfly
patterns and so learn to avoid eating noxious species, but are
also fooled into ignoring similarly marked edible species.
Ithomiines are
characterised by having small eyes, slender abdomens and long
drooping antennae that lack distinct clubs. Males have a plume of
long androconial scales or "hair pencils" on the costa of their
hindwings. These are hidden from view when the butterflies are at
rest, but are displayed when the wings are held open during
courtship. Other Ithomiine characteristics include a very slow and
deep wing beat, and a preference for inhabiting the darkest
recesses of the forest understorey.
There are basically 2 types of Ithomiine. The first type are the
black and orange-banded "tigers", many of which are mimicked by
other species due to their unpalatability to birds. The second
type are the "glasswings", recognised by their transparent or
translucent wings, prominent veins, and orange wing margins. Many
genera contain examples of both of these types, and in some cases
an individual species may produce adults of both forms according
to location.
Most novices find the Ithomiini very difficult to identify. Using
only the patterns to identify species is very unreliable because
there are so many similar species. Also many species produce a
variety of different colour forms according to locality and
season. The best approach therefore is to use the hindwing
venation and other anatomical features to identify the genus, and
to then look at the wing patterns to short-list the likely
species.
The
Giant Glasswings, which have wingspans of about 90-100mm, include 7 species of
Methona and a single species of Thyridia.
The 2 genera can be distinguished by the position of the dark cross-bar on the
hindwing, which in Methona is further out from the
base. Thyridia is noted for having shorter
antennae, and a more squarish hyaline window occupying the basal half of the
hindwings.
Habitats
Methona are primarily lowland butterflies, found in
wet rainforest at altitudes between about 200-700m above sea level.
They are
usually encountered singly or in two's and three's,
at light
gaps in the denser parts of the interior.
Lifecycle
In Peru, in the late dry
season, I observed a female
Methona confusa
ovipositing on an unidentified species of Solanaceae growing at the edge of a
narrow forest track. The butterfly spent several minutes fluttering from leaf to
leaf, "tasting" the leaves with it's feet to determine the suitability of the
plant. It eventually laid a single egg, which was large, globular, white and
glistening, on the underside of a leaf.
Methona
confusa,
Madre de Dios, Peru ©
Adrian Hoskins
Adult behaviour
Shortly after dawn both sexes
undertake short migrations. They can often be seen at this time
flying across rivers - e.g. I have observed this several times on
the Rio Madre de Dios, Peru, in August and September ( late dry
season ). During these flights they periodically pause to spend a
few minutes nectaring at herbaceous plants on riverbanks or in
forest glades.
Later in the morning as
temperatures rise they retire to within the forest. Males are
often seen at light gaps where fallen trees
have opened the canopy and allow shafts of sunlight to penetrate
to the forest floor. In such areas they perch on foliage,
typically at heights between 2-3m, to await passing
females.
I have never
observed the pre-nuptial ritual, if one exists, but have found
copulated pairs settled on low foliage at about midday. If disturbed
they fly in tandem and resettle on higher foliage.
Females are
active mainly in the late afternoon, when they slowly and very
deliberately flit about from leaf to
leaf searching for oviposition sites.
Both sexes settle
with wings closed, but I have sometimes observed males slowly
fanning their wings, possibly as a means of disseminating
pheromones.
Towards the end
of the dry season, the butterflies aggregate in the company of
various other Ithomiine species, at dry riverbeds, where they
gather at the remaining damp areas. At these times the butterflies
can often be found around the base of palms, where they hide
amongst the tent of rootlets.
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