Butterflies of the Amazon and Andes
Glycera Glasswing
Napeogenes glycera  GODMAN, 1899
subfamily - DANAINAE
subtribe - NAPEOGENINI
Napeogenes glycera polymela, Rio Kosnipata, 1500m, Peru © Adrian Hoskins
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.
This is a mid-elevation rainforest and cloudforest species found at altitudes between 600-1800m.
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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