Longwing Butterflies: Care & Information

Live butterflies and moths for sale online UK. Order eggs, caterpillars, pupae, and cocoons. Watch the lifecycle unfold with insects to rear at home!

Background

Longwing Butterflies are a distinct group of butterflies belonging to the Heliconiinae subfamily of the larger Brushfoots (Nymphalidae) family. They are so-named due to their characteristic wing shape, which is long in wingspan but short in vertical length, and are often also referred to as Passionvine Butterflies due to their unique evolutionary relationship with their Passiflora host plants.

These fascinating insects are commonly studied as models of evolution as they possess certain features and behavioural adaptations that are unique to them among all other butterflies. One of the most notable features of the genus Heliconius is the colourful array of around 100 species and subspecies which have intricate sympatric relationships with each other throughout their range of South and Central America. For example, Heliconius cydno and H. melpomene occur together almost exclusively, with only a few fragments where one species occurs without the other - recent research indicates that cydno is actually descended from melpomene, though the evolutionary split occurred millions of years ago and the differing colouration (blue/black vs red) acts as a barrier to interbreeding, as males of either species are only interested in butterflies that show their own colour forms.

Another point of interest for researchers is the feeding behaviour of Longwing Butterflies, and its role in their evolutionary success: Heliconius butterflies feed on pollen, in addition to nectar which is typical of other butterflies, and are the only known butterflies to do so. Whilst collecting nectar from flowers, pollen also sticks to the proboscis of the butterfly. In the presence of pollen, the proboscis secretes enzymes which begin to digest the pollen, breaking it down into its amino acid components which are then consumed by the butterfly. Curiously, this behavioural sophistication seems to have co-occurred with the evolution of the butterfly's brain - in Heliconius, a part of the brain responsible for learning and memory is around 3-4 times larger than that of other butterflies. This is believed to be the adaptation which allows the butterflies to remember the location of the flowering plants necessary to obtain their pollen diet, which they then revisit daily following established traplines. Such behaviour is unique among butterflies.

Eggs

Longwing eggs are sensitive to humidity and should be kept in closed plastic containers, away from direct light so that they do not overheat or dry out. The eggs hatch very quickly, after a few days, and small caterpillars require fresh host plant foliage to eat. Place a sprig of Passiflora in the container with the eggs once they start hatching, acting as a food and water source - normally we would recommend not adding host leaves, but Heliconius larvae are very tiny upon hatching and they benefit from the moisture. In nature, eggs are laid on the fresh growth of plants in shady, humid spots, so we should look to recreate this in captivity.

Caterpillars

The development of caterpillars is quick in Longwing species. The photos above show Heliconius charithonia (i) mating; (ii) laying eggs; and (iii) pupae near emerging. Between hatching from the egg and pupation, larval development only takes around 3 weeks. Room temperature is sufficient, however they do appreciate some warmth if you have a warm spot for them. Humidity is important, so mist the caterpillars very lightly if conditions are dry.

Different species tend to specialise on particular Passiflora, however those included in the Passionvine/Longwing mix will all typically feed on Blue Passionvine, Passiflora caerulea, which is the most commonly available species from plant nurseries and is very easy to propagate and grow - both outdoors and under cover. We have several large vines growing outside year-round in Glasgow, Scotland. Caterpillars do very well on living host plants if you have some small enough to fit in an enclosure, or even better in a greenhouse or conservatory, otherwise if using cut stems, they require the host leaves to be fresh so replace these when they begin to wilt.

Rearing is not at all difficult and the caterpillars will pupate within a few weeks. Typically they will suspend themselves from the host plant stems by a patch of silk, where the caterpillar forms a J-shape and completes pupation to form a chrysalis/pupa.

Pupae

Heliconius pupae are straightforward to hatch with due care. They simply require room temperature and high humidity, which can be achieved using the polystyrene box method described in the pupae care guide here. The adult butterfly will emerge in around 10 days after pupation, with the pupa becoming darker as the butterfly develops within. Soon before emergence, you can visibly see the patterns of the butterfly's wings through the pupal case, a clear indication that they are nearly ready to emerge. Note that they are most sensitive at this stage, so disturbances should be kept to a minimum.

Heliconius melpomene ecuatorialis
Heliconius melpomene plesseni
Heliconius melpomene cythera

Adult butterflies

Adult butterflies can be highly variable, even within a single species as they have multiple subspecies and geographic forms. The photos above illustrate just 3 of the Postman butterfly, Heliconius melpomene, subspecies that come from our suppliers in Ecuador. Below are multiple species of Passionvine butterflies from the butterfly house over the years.

Heliconius butterflies are very characterful and show interesting behavioural adaptations, particularly when in a large enclosure such as a greenhouse, though this is not necessary to keep them successfully. They enjoy dappled sunshine, humidity and some warmth - they also require shady spots for laying eggs if you intend to breed them, as eggs perish in sunshine.

Maintenance of these butterflies is very simple, we recommend following the care guide laid out here. They will obtain pollen from flowers, however if no flowers are available you can purchase essential amino acid powder to mix into their nectar solution as this is an excellent substitute. Remember that this part of their diet is essential to keep the butterflies alive for their full lifespan of up to six months - without it they will only live for a few weeks.