1. This study reports the discovery of sympatric populations of antlions (Neuroptera: Myrmeleontidae) and wormlions (Diptera: Vermileonidae) in a unique system of sandy microhabitats in the lowland rainforest of Borneo. The two species convergently evolved sit‐and‐wait predatory larvae, which construct pitfall traps to hunt insects. Despite similar specialised foraging strategies, the two species coexist in the competitive environment of small, isolated sandy patches in the rainforest, which begs the question: what biological characteristics allow their coexistence?

2. Based on larval morphology alone, it was predicted that antlions would build larger traps, which would allow them to efficiently hunt larger prey. Addressing this hypothesis, this study compared the volumes of traps constructed by the two species under field and laboratory conditions. A laboratory experiment compared their efficiency of capture of three ant species that differed in body size.

3. The results show that antlions constructed larger traps and captured prey more efficiently. The difference between the species could not be explained by trap size alone. The findings demonstrate that the overlap in resource use in these two species was low, and it is suggested that there is a separation in prey utility between them, allowing their coexistence in the space‐limited habitat of the tropical rainforest.