Mozart moth: Variations on a theme

LepiMAP aims to atlas not only butterflies, but also moths. Which species of moth was recorded most frequently in LepiMAP during the lockdown period starting 27 March? The top species, with 37 records between 27 March and 3 April, was Achaea lienardi, with a proposed English common name of Lienard’s Achaea. This moth is special, because it challenges the concepts that most of us have about what constitutes a “species”.

Mozart moth Achaea lienardi from Kloof, KwaZulu-Natal
This is Mark Liptrot’s photograph of Achaea lienardi from Kloof in KwaZulu-Natal. It is LepiMAP Record 713458

This photograph was taken by Mark Liptrot at his home in Kloof, KwaZulu-Natal on 3 April. Here is another moth, identified to be the same species, this time from Lüderitz in Namibia, submitted by Jessica Kemper during the lockdown period. Compare this photo with the one above.

Mozart moth Achaea lienardi from Luderitz,  Namibia
This is Jesscia Kemper’s photograph of Achaea lienardi from Lüderitz in Namibia. It is LepiMAP Record 713178

If you look closely, there are some patterns which are the same for these two records. But the colour scheme is quite different. It is hard to believe they are the same species. It turns out that Achaea lienardi is desperately variable. There is a paper written almost a century ago (Jack 1922) which says that if you make a collection of 50 of these moths, scarcely two are alike. The little white markings on the trailing margin of the hindwing are a constant feature (but can be covered by the way the moth is sitting) and the shape of the postmedial line on the forewing is diagnostic. (To find a useful summary of the names of all the features on moths, look here.) The next picture is a collage of 18 photos of Achaea lienardi submitted during the lockdown.

A collage of 18 Mozart moths Achaea lienardi from southern Africa
A collage of 18 of the Achaea lienardi submitted during the lockdown. Their LepiMAP record numbers are 711711 713178 713458 713530 713531 713540 713539 713809 714034 714035 714111 714119 714365 714565 715673 715674 716051 and 716111

Gosh, these are all the same species! Those of us who depend on colour as the cue for identifications are lost; but the members of the moth expert panel quickly pick up the pattern of the forewing, and ignore the colours. What an awesome set of variations on a theme; this is the Mozart of moths. If the white dots at the trailing margin of the hindwing are not visible, then the hindwings are being covered by the forewings. Have another look at Mark Liptrot’s photo above; the forewings are partially covering the hindwings, and the little bit of the white dots at the bottom are just visible. Quartus Grobler, member of the LepiMAP expert panel who does a lot of the moth identifications says: “This is probably the most variable of all moths.”

LepiMAP distribution map for Mozart moth Achaea lienardi
This is the LepiMAP distribution map for Achaea lienardi. It is based in 142 records from 100 quarter-degree grid cells in South Africa and eSwatini. Records up to 2019 are shown with green squares. Records made in 2020 have blue plus signs. Jessica Kemper’s record from Lüderitz is off the western edge of this map.

The distribution map shows that Achaea lienardi occurs mainly along the coastal region of the Eastern Cape, and northward into the Lowveld of eSwatini, Mpumalanga and Limpopo. The two “outlier” records in the Northern Cape and the Western Cape are not far from major citrus production regions along the Orange River and along the Olifants River (see the next paragraph). It also occurs in many parts of Africa south of the Sahara Desert. The abundance of this species varies hugely between years, and it seems to be particularly abundant in wet years. This is a species that is suspected of covering large distances in search of food. It needs energy-rich fuel to make these journeys!

This is one of the “fruit-feeding moths” and it is sometimes massively abundant in citrus orchards. There are two broad categories of fruit-feeding moths, “fruit-piercing moths” and “fruit-sucking moths”. This is a “fruit-sucking moth”; in other words it sucks the juice out of fruit which have already been compromised. The mouthparts of Achaea lienardi are too small and too weak to pierce the skin of an orange. As Hermann Staude puts it: “Their proboscis is simply not sharp and rigid enough to pierce the skin of fruit. Instead they, together with many other insects, exploit bleeding and over-ripe fruit for the sugar.” The initial damage is most frequently done by other insects, birds, tractors, etc, and sometimes the fruit simply splits as it grows. Therefore Achaea lienardi is not a moth that needs to be controlled at all in orchards. Even though this moth is nocturnal, it is often so abundant that it is the one encountered in orchards in the day time, so it is the one which takes the blame for crimes it did not commit!

Action box in banana yellow! May every LepiMAPper put a squashed banana in a saucer in their yard this evening. Let’s see what moths get attracted. Please upload them to LepiMAP. How to do this is here.

Thank you box. Hermann Staude and Quartus Grobler provided crucial information. And an especial thank you to all the LepiMAPpers who photographed and submitted records of moths from their homes.

“More reading” box! There are three more lockdown blogs:

1. Highlights of lockdown April for butterflies

2. BioMAPping at Home – Lock down on Biodiversity

3. Blue Sky Birds: BirdPixing blues: look up and see birds

To finish. Here are two earlier records of the “Mozart moth” Achaea lienardi, selected from the 192 records in total for the species in LepiMAP.

Mozart moth Achaea lienardi from Amanzimtoti, KwaZulu-Natal
This is Michael Purve’s photograph of a curled-up leaf. No wait, it is Achaea lienardi from Amanzimtoti in KwaZulu-Natal. This was the first record of the species to be submitted LepiMAP. It is Record 15896 and is dated 5 January 2011.
Mozart moth Achaea lienardi from Mwambwa Field Station, coast of Kenya
This is David Clarence’s photograph of Achaea lienardi from the Mwamba Field Centre, on the Kenyan coast. It is LepiMAP Record 646907 and is dated 30 April 2018.

Les Underhill
Les Underhill
Prof Les Underhill has been Director of the Animal Demography Unit (ADU) at the University of Cape Town since it started in 1991. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics. He was awarded his PhD in abstract multivariate analyses in 1973 at UCT and what he likes to say about his PhD is that he solved a problem that no one has ever had. He soon grasped that this was not the field to which he wanted to devote his life, so he retrained himself as an applied statistician, solving real-world problems.