Zebra Longwing Butterfly (Heliconius charithonia)
By Beatriz Moisset
The zebra longwing butterfly or zebra heliconian, Heliconius charithonia, is unmistakable with its long narrow wings, which are striped black and pale yellow. This species is common in Mexico and Central America and it is also found in most of Florida and in some areas of Texas, where it can be seen year round. Occasionally it wanders farther north as far as South Carolina and some of the central states, although it is not likely to survive the cold. Florida designated this striking creature as its state butterfly in 1996.
They fly slowly and gracefully and are not easily startled. They gather in roosts to spend the night returning to the same place daily; all this making it easy to observe them. After mating the female lays eggs on one of several species of passion flower plants Passiflora. The caterpillars feed on these plants and acquire some of their toxins; this makes them distasteful to predators. The striking colors and pattern of the adults advertise their toxicity.
An unusual feature of the longwing, or heliconian, butterflies is that the adults are relatively long lived. Most other butterflies live only a few weeks, but heliconians continue to live and to lay eggs for several months. Their tropical or semitropical habitat makes this possible; furthermore the feeding habits of the adults are important in prolonging their lives. The adults feed on nectar of flowers, like most other butterflies, but a special characteristic of heliconian butterflies is that they can also feed on pollen.
Most butterflies can only sip fluids with their specialized mouth parts, but the heliconian butterflies take some pollen as well as nectar. Their saliva enables them to dissolve the pollen and to take their nutrients. Pollen is very nutritious, rich in proteins, unlike nectar which contains almost no proteins, just sugars. This diet allows the butterflies to prolong their lives and also enables them to continue producing eggs for several months. As a consequence they are more dependent on flowers than other types of butterflies and this makes them good pollinators. They feed on a wide range of flowers; some of their favorites are lantana (Lantana, Verbenaceae family) and shepherd's needle (Bidens pilosa, Asteraceae family). It is also possible that they develop a sort of symbiosis with those plants that provide their preferred pollen.
Zebra longwing and other heliconians have a reputation for being very intelligent insects. They have a social order when roosting; the oldest ones choose the best places. They also gently nudge the others early in the morning to get going. Another interesting characteristic of heliconian butterflies is that they can remember their food sources and return daily to the plants where they fed previously, a behavior known as trap lining. The memory is so strong that if one shrub in their route is cut down they return to the location again and again only to search in vain.
A relative of this butterfly, the Red Postman (Heliconius erato), is seen occasionally in Texas. It is also very beautiful, black with white and red markings. Its life style is similar to that of the zebra longwing.