The western corn rootworm, Diabrotica virgifera virgifera LeConte, is one of the most deleterious pests of corn worldwide. Severe root injury interferes with the roots` ability to absorb water and nutrients and results in plant lodging and yield losses. After the pupation in the soil, the emerged adults primarily feed on leaves, corn silk, pollen, and kernels on exposed ear tips of corn. An absolute sampling method for adult western corn rootworm was developed exploiting the strong positive phototropic and negative geotactic behaviour of this coleopteran species. The novel developed pyramidal designed emergence trap is characterized by numerous features which facilitate the estimation of western corn rootworm populations in the field: The trap is highly efficient, simple and economical to construct, portable, easy and quick to install, durable and thus nearly maintenance-free. The installation of the trap relies on cutting corn plants at a height of 20 cm. Both the efficacy of recapturing of ten released beetles per trap and the possible negative influence of corn plant cutting on the subsequent larval development and adult emergence was investigated in a field study performed in South Tyrol (Italy) in 2015. With our pyramidal designed system, on average 99% of the beetles were recaptured within two days after releasing in the traps. Cutting corn plants shortly prior to the expected adult emergence did not significantly influence the total number of emerged beetles. Although the efficacy of this trap has been proven only for Diabrotica v. virgifera, it might be tested for other rootworm species and insects with similar behavioural characteristics.