Butterflies of the
Amazon and Andes
Julia, or Flambeau
Dryas iulia
FABRICIUS, 1775
Family - NYMPHALIDAE
subfamily -
HELICONIINAE
Tribe - HELICONIINI
Dryas iulia, Rio Pindayo, Peru
� Adrian Hoskins
Introduction
The Heliconiinae is divided
into 3 tribes Acraeini, Argynnini and Heliconiini. The latter are
colloquially known as Longwings and are confined to the neotropical
region. They are easily recognised by their distinctive patterns,
elongated forewings and characteristic delicate fluttering flight.
The subtribe
Heliconiini includes Heliconius ( 39
species ), and the smaller genera Dryas,
Podotricha,
Philaethria, Laparus,
Eueides, Neruda,
Agraulis, Dione
and Dryadula.
The dazzling orange
Dryas iulia is widespread and common in
the southern United States, Central America and much of the
Caribbean, and occurs throughout all of the tropical and subtropical
areas of South America.
Dryas iulia, Rio Madre de Dios, Peru
� Adrian Hoskins
Mud-puddling
In tropical regions
males of many species visit sandbanks, riversides and damp paths to
indulge in 'mud-puddling', i.e. visiting patches of damp ground where
they filter-feed by continually pumping water through their bodies
while extracting dissolved minerals. The filtered water is often
squirted back onto the ground to dissolve further minerals which are
reimbibed. These chemicals are passed to females via spermatophore
during copulation. Males which have already mated usually return to
replenish their salts, and afterwards often mate again with another
female. Females don't normally mud-puddle - they feed instead on
nectar, visiting herbaceous plants and flowering trees.
On the sandbanks, initially just one male will chance upon a suitable
feeding spot, but other males flying past seem able to recognise their
brethren on the ground, and swoop down to join them. The bright patch
of colourful butterflies quickly becomes a magnet to every passing
male of the same species, and after an hour or so hundreds or even
thousands of butterflies may assemble at certain particularly
mineral-rich sandbanks.
Normally several different species are present at these feeding
places. It might be expected that the various species would be
randomly distributed on the ground but this is not the case. Each
butterfly polarises very strongly towards it's own brethren, so that
each species congregates as a discrete group.
In calm weather
the butterflies in each group are positioned randomly, but on river
beaches there is usually a constant gentle breeze, so all the
butterflies tend to face into the breeze. In this way they are less
likely to be blown about and lose their feeding spot to a competitor.
Habitats
The
butterflies fly in rainforest and deciduous forests, but are
commonly encountered in disturbed open habitats such as forest
clearings, cattle pastures, along riverbanks, and in flowery
gardens.
Dryas iulia, Catarata Bayoz, Peru
� Adrian Hoskins
Lifecycle
Like
most other Heliconiines, the Julia lays it's eggs on
Passiflora ( Passion flower ). There
has been a great deal of study into the relationship between these
plants and Heliconiine butterflies, which strongly suggests they
they co-evolved. There is a constant evolutionary battle in which
the plants try to defend themselves from the butterflies. Some
Passiflora vines for example produce
false stipules at the base of leaf stems, that induce egg laying by
certain Heliconiine species. A day or two later the stipules drop
off, carrying the eggs with them. Eggs which fall to the ground
probably get eaten by ants, but even if they survive, the resulting
larvae will starve. Certain other Passiflora
vines produce tiny tubercules on the stipules that mimic Heliconiine
eggs. Any butterfly visiting the plant sees the false eggs, is
misled into thinking that the plant is already overladen with eggs,
and is consequently inhibited from ovipositing.
The
body of the multicoloured caterpillar is adorned with long black
thorny spines, with a further pair arising from the head. It feeds
openly in the daylight.
Adult behaviour
Males often gather in
small groups to drink at damp mineral-rich sites such as salt-licks,
sandbanks, peccary wallows, or urine-soaked earth. They are also
regularly observed sipping liquid from the corner of the eyes of the
yellow-throated caiman in Brazil, or from the eyes of turtles in Peru!
Dryas
iulia, Brazil
� Miguel Antonio-Silva-Stefanelli
Females behave
differently, visiting flowers including Lantana,
Eupatorium and various canopy species,
but as well as drinking nectar they feed on dissolved pollen, from
which they obtain nutrients that have been shown to be essential to
egg production.
I have not observed the
courtship, but in Costa Rica have found mated pairs resting on low
foliage with wings closed, in early afternoon. When copulated the
butterflies are very reluctant to fly.
Dryas iulia, Catarata Bayoz, La Merced, Peru
� Adrian Hoskins
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