Butterflies of
the Amazon and Andes
Common Longwing
Heliconius erato
LINNAEUS, 1758
Family -
NYMPHALIDAE
subfamily -
HELICONIINAE
Tribe - HELICONIINI
Heliconius
erato luscombei, Rio Madre de Dios, Peru
Introduction
The tribe Heliconiini, colloquially known as Longwings, includes 71 species, all
confined exclusively to the neotropics.
The Heliconiini includes
the genera
Heliconius, Podotricha, Dryas, Agraulis, Dione, Dryadula, Eueides, Neruda, Laparus
and Philaethria.
All Heliconius species have elongated
black wings, marked with simple but striking patterns usually
featuring streaks or patches of red and cream, or blue and cream. A few,
such as
sara,
antiochus
and
wallacei have a metallic blue sheen over the basal area of both wings. All are
characterised by their delicate fluttering flight, long straight antennae, and
fondness for flowers.
The 39 Heliconius species are much
studied by geneticists and taxonomists. Many of them produce a
staggering variety of colour forms -
Heliconius erato e.g. produces no less than 29 geographical
forms, each of which corresponds almost exactly in colour and
pattern to a "sister" subspecies of
Heliconius melpomene flying in the same area.
Heliconius
erato microclea, Satipo, Peru
There are often
striking differences between the different forms of each species, as can be seen
in the illustrations above. In some subspecies of erato
the cream patch on the forewing is reduced to a group of dashes in the shape of a claw.
In others it is replaced by a pair of large
orange patches or
may even be entirely absent. The basal
area of the forewings is usually red, but may be unmarked in some races. The
hindwing markings may be red, orange or cream, either in the form of radiating
lines, or as a solid median band.
Perhaps the most dramatic variety is
cyrbia, which has a lurid pink band across the
forewings, white submarginal rays on the hindwings, and a beautiful metallic
blue sheen across the entire wing surface.
Heliconius erato is
probably the commonest and most widespread Heliconiine. It's 29
subspecies are distributed across the neotropical region from Mexico to
Brazil, Bolivia and Argentina. The illustrated subspecies luscombei is
confined to the Amazonian lowlands of south-eastern Peru, while microclea
is restricted to mid-elevation sites in central Peru.
Habitats
This species occurs commonly at elevations between 0-1800m on
both sides of the Andes. It can be seen flying in two's or three's around
clearings, and along roads and tracks through primary forest. It is commoner
however in secondary forest, and can be found flying in coffee plantations,
gardens, orchards and along roadsides and forest edges. In regions such as
Guanacaste where seasonality is pronounced, it is common in forest / pasture mosaics
during the rainy season, but abandons these in favour of more heavily
forested areas in the dry season.
Lifecycle
The eggs are yellow, and laid singly on the leaf tips of
Passiflora.
The
caterpillars are aggressively cannibalistic. When fully grown they are white,
dotted with black and have branched black
spines on the back and sides. The head is straw coloured with a pair of
recurved black spines. The chrysalis is brown with golden spots on the abdomen and thorax. It
has
short black spikes on the abdomen and along the costa of the wing cases. The
head is bifid, with the labial palpi extended and twisted. The overall
impression is of a decaying dead twisted leaf, hanging from a stem.
H. erato amazona / venustus, sequestering pollen from "hotlips" flowers
Psychotia poeppigiana
Adult behaviour
Heliconius butterflies are characterised by
having a very delicate fluttering flight, particularly when hovering
around flowers. They commonly nectar at
Hamelia, Lantana and
Palicourea.
Unlike other butterflies,
Heliconius females feed on pollen as well as
nectar.
Studies of ethilla have shown that
females deprived of pollen can only produce about 15% of the number of
eggs laid by females that have
access to it. This probably applies equally to other
Heliconius species including
melpomene. The pollen from
Psiguria,
Anguria and Gurania flowers provides amino
acids
that can't be obtained from nectar or other sources, and contributes
greatly to the longevity of the butterflies - some
Heliconius species are known to live for up to
9 months as adults.
Studies have shown that
Heliconius butterflies have home
ranges within which they can memorise the locations of nectar and
pollen sources, host plants and communal roosting sites. They are
able to plan the most efficient route by which to visit all nectar
/ pollen sources in the vicinity by using simple calculations akin
to what mathematicians call the "travelling salesman algorithm". Erlich & Gilbert demonstrated
that individual butterflies memorise the location of particular
Psiguria plants, which they visit daily, following a
predefined circuit through the forest.
In the genus Heliconius most species
rely entirely on airborne chemicals to locate mates. Males of
hecale,
ismenius and cydno are attracted by pheromones to the pupae of conspecific females.
The day before emergence a female pupa will usually have
several males in close attendance. A frantic battle
takes place the instant she hatches, as the males all struggle to copulate with her, not even
allowing her time to
expand and dry her wings. In some other
Heliconius species such as
hecalesia,
hewitsoni, erato,
charithonia and
sara the males don't even wait until the female emerges.
Instead they physically break open her pupa and copulate as soon
as her genitalia are accessible.
Heliconius erato adults roost
gregariously overnight, hanging in clusters of up to 10 from dry
stems, usually quite close to the ground.
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