Heliconius erato emma, Rio Pindayo, Peru – Adrian Hoskins
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 – Adrian Hoskins
There are often striking differences between the different forms of each species, as can be seen in the illustrations here. 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, and petiverana is Central American.
Heliconius erato petiverana, Costa Rica – Maris Pukitis
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.
Heliconius erato chestertonii, Medellin, Colombia – Adrian Hoskins
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.
Heliconius erato chestertonii, Medellin, Colombia – Adrian Hoskins
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.