Waves of white butterflies move across SA
SOCIAL media and news sites have been abuzz as people posted several sightings of swarms of white butterflies flying across the northern parts of South Africa over the past week.
But what many regard as the migration of these butterflies is instead “dispersal events”, the Lepidopterists Society of Africa (LepSoc Africa) said.
In a statement, LepSoc Africa dismissed some of the myths and misconceptions about the movements of these swarms of butterflies.
Also known as the brown-veined white in South Africa, the butterfly Belenois aurota occurs in southern Asia, as far east as India and the Himalayas, in southern Arabia and throughout most of sub-Saharan Africa.
“Most of the butterflies being seen in Joburg and surrounding areas are pioneer caper whites (Belenois aurota),” LepSoc said.
Although it was also the largest “migration” since 1966, it said the phenomena being witnessed at present was not a true migration as the butterflies would not return.
They were largely flying from the drier south-western areas to the wetter north-east areas.
The core population of Belenois aurota in South Africa was the Kalahari region, where the larvae fed on Shepherd’s trees (Boscia albitrunca).
The dispersal, which was due to a population explosion, was expected to last for a few weeks. And while climate change was considered a factor in these phenomena, the research data were not conclusive, LepSoc said.
“We don’t think there is adequate data to suggest that climate change is responsible for the current wave of pioneer caper whites. Years of drought led to drastic reductions of the predators that feed on Belenois aurota, primarily the eggs, larva and caterpillars. These predators may be viruses, parasitic wasps, robber-flies, spiders and birds, among others. Usually about 99% of butterfly early stages are eaten. Good rainfall, as we’ve experienced recently, leads to favourable conditions and a population explosion of Belenois aurota and a subsequent ‘migration’.”
LepSoc disputes the butterfly, in any of its stages of metamorphosis, constitutes a threat to agriculture. “Belenois aurota caterpillars feed only on plants of the caper family; they are not an agricultural pest and will do no damage to suburban gardens; their caterpillars are not army worms or lily borers, nor will they cause African horse sickness.”
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