Infrequently observed at Verloren Valei, the Basuto Skolly or Basuto magpie has a somewhat disreputable reputation, as its name implies.
By Justin Bode
Thestor basutus, Basuto Skolly or Basoetoe Skollie, is the most widely distributed species in its genus. While most of the genus is found only In the Western Cape, this species is found from the Eastern Cape and northwards.
It is the only species of the genus that is not endemic to South Africa.
The Basuto Skolly would appear to be rare at Verloren Valei, with only two records from the reserve recorded on LepiMap. The most recent of these dates from January 1992.
Adult Skollies lack a functioning proboscis and therefore do not frequent flowers and all their energy needs to be stored up in their larval stage. In their larval stage, they are fed by the so-called pugnacious ant, Anoplolepis custodiens, so their eggs are generally laid in soil or on rocks or vegetation (live or dead) close to ants’ nests or trails. The larvae of Basutu Skolly are hemipterophagous (feed on blood) in the first three instars. A 2nd instar of Basuto Skolly has been observed to feed in nature on an immature psyllid (plant lice). It is considered that 1st and 3rd instars are similarly predatory but in later instars they are probably fed directly by their host ants by trophallaxis (mouth to mouth feeding).
Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth or mouth-to-anus feeding. Apart from the transfer of nutrients, it is also thought to act as a way of communicating and building community bonds. It is used by some birds, gray wolves, vampire bats and is most highly developed in social insects like ants.
In this instance, the butterflies are effectively parasitic. It would appear that, like a cuckoo, the Basuto Skolly has adapted to provide a way of fooling the ants to provide food.
In Greek mythology Thesor was a Trojan, and it can be assumed the genus derives its name from it being a “Trojan Horse” in the ants’ nest.
Thestor basutus is usually found in small colonies close to Anoplolepis host ants, but some Cape Mountain species may number in the hundreds.
The flight is slow and close to the ground. When disturbed, however, they can put on a considerable turn of speed. The male perches on ground or low vegetation, chasing after intruders while the female are more sedentary and skulking.
They are double brooded are and on the wing in October and November and in February to April.
MC Williams, Afrotropical Butterflies, www.metamorphosis.org.za, February 2022
S Woodhall, Field Guide to Butterflies of South Africa. Struik, Cape Town, 2020