Many species of nymphalid butterflies only exceptionally visit flowers and
feed instead on tree sap, juice of rotting fruits and other decaying substa
nces. To investigate whether the proboscis morphology of these non-flower-v
isiting Nymphalidae differs from that of nectarivorous butterflies, represe
ntatives from 64 nymphalid species with known feeding preferences were exam
ined. Morphometric comparison of the proboscis revealed characteristic diff
erences in proboscis length, tip-region length, wall composition, and numbe
r and shape of proboscis sensilla between these two feeding guilds. The inv
estigated non-flower-visiting species belonging to Apaturinae, Limenitidina
e, Morphinae, Brassolinae, Nymphalinae and Satyrinae, possess a relatively
short and light-coloured proboscis which has a long tip-region with a great
number of club-shaped sensilla styloconica. Densely arranged, these sensil
la form a flat brush located laterally from the openings into the food cana
l on the dorsal side of the tip-region. Among the non-flower-visiting speci
es, a second type of proboscis was found in fruit-feeding Charaxinae the st
out tip-region of which is equipped with more widely spaced sensilla styloc
onica. The investigated flower-visiting Heliconiinae, Nymphalinae, Satyrina
e, Danainae and Ithomiinae are characterized by a slender, darker-coloured
proboscis with a rather short tip-region bearing fewer sensilla styloconica
in a loose arrangement. Discriminant analysis revealed that the tip-region
length, the number of sensilla styloconica and the relative proboscis leng
th are the most important discriminating variables between the flower-visit
ing and the non-flower-visiting species. The proboscis morphology of nympha
lid butterflies corresponds with certain feeding habits and allow us to mak
e predictions on their food preferences. The 'brush-tipped' proboscis seems
to have a functional role in the accumulation of fluid and the uptake of l
iquid from wet surfaces such as rotting fruits or tree sap. We conclude fro
m the phylogeny of the examined taxa that this derived proboscis lip morpho
logy evolved several times independently as an adaptation to the exploitati
on of new food resources.