Pseudomyrmex ejectus at the nest entrance (Florida, USA)

Why are Elongate Twig Ants (Pseudomyrmex species) so slender?

All the better to fit into the narrow crevices of their twiggy lodgings:

Pseudomyrmex twig ants don’t carve their own nest chambers the way most other ants do. Rather, they inhabit old burrows in twigs and stems dug by the larvae of other insects, especially beetles. Their flexible, elongate bodies allow them to maneuver in tight cavities:

Elongate twig ants comprise about 200 species found in the tropics and subtropics of the Americas. Their above-ground nesting preferences make them vulnerable to winter freezing, which is presumably why they don’t extend far into the temperate zones. That’s a real shame for we northern myrmecophiles. With the exception of a handful of hyper-aggressive ant-plant species, Pseudomyrmex are delightfully gentle, quirkly little insects.