Visitors to South Africa travelling through Gauteng, Mpumalanga and Limpopo
recently, must have noticed that they were in the company of thousands of little
white butterflies, fluttering steadily in more or less the same direction. These
are the brown-veined whites (known in Afrikaans as the grasveldwitjie), the
colouring of the undersides of their wings giving them their name, their scientific
name being Belenois aurota.
The butterflies originated from the Southern African interior, where most of their
larval hostplants grow naturally. The good rains in January and February and
the subsequent rush of new leaves saw the females laying their eggs on their
specific food plants in great abundance. Within days millions of tiny caterpillars
hatched and ate their way steadily but surely “out of house and home”.
These caterpillars then pupated
and emerged as butterflies, to
go in search of a mate and a new
food plant to lay their eggs upon,
and so the cycle continues until
the larval food plant supply is
finished. This phenomenon is known
as population explosion.
Adults that have as yet not procreated
will disperse to look for their food
plants elsewhere and will somehow
keep moving in a south-easterly direction
towards the sea off Mozambique. Most will unfortunately perish en route due to total exhaustion.
A few nectar plants in your garden helps to sustain the travellers.
Reproduced from an article by Lieveke Noyons