These white butterflies have been spotted in provinces such as KwaZulu-Natal, Gauteng, Free State and Northern Cape, leaving many wondering what they are and where they come from.

JOHANNESBURG - Over the past few weeks, South Africans have been treated to the wonderful sight of white butterflies flying across the sky.

These butterflies have been spotted in provinces such as KwaZulu-Natal, Gauteng, Free State and Northern Cape, leaving many wondering what they are and where they come from.

Everyone go outside and look at the beautiful white butterflies migrating through Jhb today 🦋 — IlhaamHoosen (@IlhaamHoosen) January 28, 2020

@Eusebius @Radio702 They’re everywhere lol. The white looking butterflies. This is in Sandton right now pic.twitter.com/qmi1zYueVb — IG: bosssindim (@SindiMzizi) January 28, 2020

Most parts of Sandton are covered in white butterflies this morning. ⁦@MbauReloaded⁩ are you getting married? pic.twitter.com/VTI7lPwe2I — Wendel Bloem (@WendelBloem1) January 28, 2020

Watching hundred and thousands of little white butterflies fly through the neighbourhood. It’s beautiful. pic.twitter.com/0yUq0Ohyhu — Marco Cocomello (@Cocomelts) January 28, 2020

Eyewitness News spoke to Dr Vaughn Swart from the Zoology and Entomology department under the University of the Free State's faculty of Natural and Agricultural Sciences to understand more about these butterflies.

Dr Swart explained that the official scientific name of the butterfly species is Pieridae and in simple terms, the butterfly is known as the brown-veined white butterfly. What's happening is called the annual white butterfly migration, which happens around mid-summer time in South Africa.

"The butterflies originate from arid places in the country such as the Karoo and head in a north-easterly direction towards Mozambique and northern KwaZulu-Natal."

Dr Swart said the butterflies are an important part of the ecosystem as they serve as food for other insects and birds.

The number of butterflies migrating every year depends on the food available to them from the areas they originate, which in term affects how they pupate and lay eggs. Numbers differ from year to year.

"It can take between two to four days for the brown-veined white butterfly to reach its destination as it flies across the country," Dr Swart explained.

They’re here! The annual mid summer butterfly migration descends on the garden where I work. I used this annual migration in a scene in JOHANNESBURG. The white, brown-veined butterflies are heading for Mozambique. Millions float across the city on their journey. Exquisite! pic.twitter.com/JMDgExx27T — Fiona Melrose (@FMelroseWriter) January 28, 2020