Butterflies of
the Amazon and Andes
Glycera Glasswing
Napeogenes glycera
GODMAN, 1899
Family -
NYMPHALIDAE
subfamily - DANAINAE
Tribe - ITHOMIINI
subtribe -
NAPEOGENINI
Napeogenes
glycera polymela,
Rio Kosnipata,
1500m, Peru.
Introduction
The Ithomiinae 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 Ithomiinae 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
genus
Napeogenes
contains 22 known species of small to medium sized Ithomiines. Some such as
tolosa
and
duessa
are marked with large patches of orange and cream on a black ground colour,
while others, including
glycera,
larilla
and
harbona
fall into the "Glasswing" category, with largely transparent wings, marked on
the under surface with orange and black, and a series of white submarginal
spots.
Napeogenes glycera
occurs in Ecuador, Peru and Bolivia.
Habitats
This is a mid-elevation rainforest and cloudforest species found at altitudes
between 600-1800m.
Lifecycle
The eggs are white, and laid singly on the underside of
leaves of Solanum ( Solanaceae ).
Adult behaviour
Males gather in two's and
three's in light gaps, where they feed at pyrrolizidine alkaloids,
chemicals which are exuded by decomposing leaves, flowers and
stems. These chemicals are converted by the butterflies into
defensive toxins, and into pheromones that are used to entice
mates.
The butterfly in
the photograph above is feeding from the decomposing corpse of an
insect which is trapped in a spider web. Females also feed at
flower nectar, and at bird droppings.
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