Levuana Moth

A plague for the coconut industry

Beginning around the 1870s, swarms of moths started destroying coconut plantations. In this way, the Levuana moth became a serious pest of coconut plants on Viti Levu, the main island of the Fiji group in the South Pacific.

At first, the Levuana or coconut moth was found only on the island of Viti Levu, but little by little it also colonized neighboring islands, including Vanua Levu, the most important island for coconut production. Because of the absence of predators or parasites, the Levuana Moth population steadily increased until it was finally regarded as a pest. The main problem was that the moth’s larvae fed on the leaves of coconut palms.

This meant that not enough copra—dried coconut kernel flesh used to obtain coconut oil—could be harvested. Coconut cultivation became increasingly unprofitable. Alongside sugar, copra is one of the most important industries in the Fiji group. The Fijians, the indigenous population of Fiji, depended on coconuts, because they served as a source of food and drink, provided fiber and were used as medicine, fuel and building materials.

Levuana moth – fact sheet

alternative name	purple leaf moth, coconut moth, cocoanut moth
scientific names	Levuana iridescens, Levuana irridescens
original range	Viti Levu (South Pacific)
time of extinction	1925 at the earliest
causes of extinction	biological control program
IUCN status	extinct

Biological control program dramatically reduced the moth population

Numerous attempts were made to reduce the coconut moth’s population, but all of them failed. Only a biological control program in 1925 proved effective. The Canadian entomologist John Douglas Tothill proposed introducing a parasite that would minimize the Levuana Moth population.

Since no such parasite existed in Fiji, Tothill introduced the Malaysian parasitic fly species Bessa remota. It proved very successful in controlling the pests—perhaps too successful.

In his 2003 publication, Armand M. Kuris writes that the 1925 control program was the first and best-documented eradication of a species by means of a biological control program. It is easy to see why the program was subjected to fierce criticism, since it involved the systematic eradication of a unique species in favor of the copra economy of Pacific island inhabitants.

In an article for the University of California, entomologist Mark Hoddle advances the thesis that Bessa remota was responsible not only for the eradication of the Levuana moth but also for that of another species: Heteropan dolens. This was a species from the burnet moth family (Zygaenidae) endemic to Fiji. The Levuana moth also belongs to this family.

Levuana moth: not extinct after all?

There had been no documented sightings of Levuana since the 1920s. According to Hoddle, the last animal was collected in 1929. Some experts nevertheless assume that the moth may have survived until the mid-1950s.

Because the Levuana moth preferred tall coconut palms and only moved to shorter palms when these had no leaves left, it is possible that a small population may have survived to this day. If only a few of these moths remain and their preferred feeding sites are high up, searches on immature coconut palms will be unsuccessful.

Some experts, such as Kuris, assume that if the Levuana moth still exists, it no longer inhabits Viti Levu, but only neighboring islands.

---