Butterflies of
the Amazon and Andes
Dardus Underleaf
Eurybia dardus
FABRICIUS,
1877
Family - RIODINIDAE
subfamily -
RIODININAE
Tribe - EURYBIINI
Eurybia
dardus annulata, Mariposa, Satipo, Peru
© Steve Meredith
Introduction
There are about 20
Eurybia
Underleaf butterflies, which occur variously throughout the neotropics from
Nicaragua and Honduras to southern Peru and Bolivia.
All have greyish or brownish uppersides with a series of
squarish submarginal markings. Several species e.g.
molochina
and
lycisca
have a blue iridescence across the upperside hindwings.
Almost all species have a prominent orange-ringed false eyespot in the discal cell of each forewing. Only
halimede, albiseriata, elvina
and the falcate-winged
carolina
and
pergaea lack these eyespots, and hence are commonly known as "blind" underleafs.
In
all species the
upperside pattern is repeated on the under surface, but the under surface is
paler, and the markings less conspicuous.
Other
Eurybia characteristics include
metallic green eyes and an extremely long proboscis that is almost
twice the length of the body, enabling the butterflies to reach
deep into flowers for nectar.
Eurybia
dardus is known from Colombia, Venezuela, Surinam, Brazil, Ecuador and
Peru.
Habitats
This species occurs in primary rainforest at elevations
between about 400-1500m. The butterflies are rarely seen in open sunlight,
instead preferring the darkness of the forest understorey.
Lifecycle
I have no data regarding
dardus but the lifecycle is likely to be
very similar to that of other Eurybia species as
follows: The eggs are like flattened lozenges and are laid singly on the stems
and leaves of Calathea,
Ichnosiphon, Maranta,
( Marantaceae ), Costus and
Renealmia ( Zingiberaceae ). The larvae are maggot-like, and feed on the flowers,
not the foliage. Older larvae can be found in ant nests within sheaths
surrounding the stems of the foodplants. They are constantly
attended by ants which milk them for a sugary substance secreted
from a dorsal gland. The larvae are parasitised by
Rogas and other Braconid wasps.
The proboscis on the
butterflies is very long, and there is a correspondingly
long-proboscis casing on the pupa, which extends about 2cms beyond
the tip of the abdomen.
Adult behaviour
The adults are very secretive by nature, spending long
periods resting under the leaves of low growing vegetation, with wings spread open,
while almost cheekily peering
out to keep a watchful eye on human intruders.
Periodically they dash out to investigate other butterflies, but
instantly return to settle under another nearby leaf. The speed of
flight is extraordinary, and the degree of agility apparent when they
fly into the vegetation, flip upside-down and settle under a leaf
is quite amazing to behold.
All
Eurybia species have an extremely
long proboscis which enables them to
probe for nectar into the deep flowers of
Heliconia plants. The easiest way to observe the
butterfly is to find an isolated
Heliconia growing in the forest, and to wait
nearby until one arrives.
DeVries records that large numbers of
Eurybia adults are eaten by Anolis
and Norops lizards.
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