A third of tiger beetles never touch the ground — the arboreal specialists

Walk through the rainforests of Borneo, Sri Lanka, or the Amazon and you might never see a tiger beetle — because the ones that live there are above your head. A full 30 percent of the 3,700 species in the family Cicindelidae have abandoned the ground entirely, evolving into specialist hunters of the forest canopy.

Six tribes, one convergent solution

Arboreal life has evolved independently in at least six lineages. The most spectacular is tribe Collyridini — nearly entirely arboreal, with slender cylindrical bodies perfectly adapted to sliding between bark crevices. Collyris of South and Southeast Asia, Tricondyla with their elongate pronotum, Therates hunting on fallen logs — each is a variation on the same theme: abandon the ground, colonise the vertical world.

In the Neotropics, Ctenostoma evolved the same solution independently. In Madagascar, Pogonostoma and Oxygonia dominate the arboreal niche. Even within primarily ground-dwelling tribes like Cicindelini, genera such as Physodeutera and Pentacomia have shifted to bark and branch.

How arboreal tiger beetles hunt

Ground-dwelling tiger beetles rely on speed — pursuit predation in open terrain at up to 9 km/h. Arboreal species have abandoned this strategy. Most are ambush predators, flattening themselves against bark and waiting. Their compound eyes are proportionally smaller than those of open-ground species — less useful in broken forest light. Their legs are longer and more slender, gripping bark rather than sprinting.

Many arboreal species are crepuscular or nocturnal, active in the hours when the forest canopy cools and insects emerge from bark fissures. Tricondyla species in Borneo are among the few beetle genera observed hunting actively at night on tree trunks, using chemical cues rather than visual pursuit.

Where to find them — bioregional breakdown

Arboreal Cicindelidae are overwhelmingly concentrated in the wet tropics. The Oriental region dominates with Neocollyris (297 species), Therates (186), and Tricondyla (57) as the three largest arboreal genera globally. The Neotropical region contributes Ctenostoma (147 species) and Pogonostoma (122 species in Madagascar's Malagasy region).

In contrast, the entire Palearctic region — Europe, temperate Asia, northern Africa — has almost no arboreal Cicindelidae. The handful of arboreal Cicindela species from Himalayan and Chinese forests are striking exceptions that prove the rule: arboreal specialisation requires year-round forest humidity and stratified canopy.

What the matrix reveals

The 194-character Cicindelidae matrix records habitat type at species level across all 3,717 taxa. Analysing the sk_habitat_type field reveals that "arboreal" is not a single category — the matrix distinguishes arboreal-bark, arboreal-canopy, arboreal-fallen-log, and arboreal-bamboo specialists. Combined, these categories account for 1,116 species, or 30.0% of the family. The figure cited in older literature of "about one third" turns out to be almost exactly right.