Technomyrmex pallipes: Pallid-footed Ants

DOLICHODERINAE

 INVADER ?

Several species of White-footed ants, or Technomyrmex, have become serious invaders around the world, including Technomyrmex albipes and T. difficilis. The genus is large with some 98 species; we have six in Southern Africa, most of which are obscure and seldom seen. One, T. pallipes, the Pallid-footed ant, is widespread. The jury is still out on whether this ‘tramp’ species is indigenous or not. The various invasive White-footed ants apparently originate from Indonesia.

Robertson et al classified this ant as T. albipes in 1990, but subsequently many experts have preferred T. pallipes, and the good news is that there has only ever been one record of T. albipes in southern Africa – in Johannesburg, on goods imported from Mauritius. The difference between the species has mostly got to do with the position of bristles or setae on the body, not something easy to distinguish in any event on these very tiny animals. The ants are jet black with pale legs and are smaller than Argentine ants, with proportionally-larger gasters (abdomens). They are able to displace Argentines from dwellings but not, as far as we know, from gardens. How they achieve this is not clear, but it seems that they exude some kind of poison from their anal glands that eventually kills their opponents.
They are mostly nocturnal and seem to favour kitchens and bathrooms, but in cold climates are particularly notorious for their habit of nesting in electrical appliances, circuit-boards etc, often causing the malfunctioning or destruction of these tools. 

The ants reputedly spread by budding (I have never seen this, but it might happen at night), and queens reputedly sometimes run with the workers in the trails. These ants also make use of ergatoid queens, adapted workers which are larger than usual, and can mate with males and lay eggs.

Colonies can be very large or quite small, and the ants seem to favour wooden structures such as window frames, etc. as nest sites (when they’re not invading electrical goods, that is). They are easily mistaken for Lepisiota capensis, which is also often invasive, but Lepisiota are larger [2.5 to >3mm], and not normally nocturnal. When in doubt, open a nest and you’ll find that Lepisiota’s pupae are always in cocoons, whereas Technomyrmex are always naked. Finally, Technomyrmex have a rather foul smell when crushed. The drawings below compare the two.

Survive invasive species:
Linepithema humile       : Argentine ants       : Yes
Pheidole megacephala  : House ants            : unknown
Lepisiota sp.                  : Small Black ants    : unknown
Technomyrmex albipes : White-footed ants  : unknown
Anoplolepis gracilipes   : Yellow Crazy ants  : unknown