The construction of a simulated-ear-insect-trap (SEIT) for ear-feeding black flies is described. The SEIT, which consists of a styrofoam container with dry ice and a mock sticky ear mounted on a tripod, was developed to capture Simulium jenningsi Malloch and S. vittatum Zett., both widespread pests of livestock. SEIT units set on horse farms within 5 km north of the Potomac River in south-central Maryland, USA (n = 36 samples of 30 min each), consistently captured S. jenningsi and S. vittatum (
and 7.1 per sample, respectively), whereas units set simultaneously on farms > 5 km north of the river (n = 99 samples of 30 min each) captured progressively fewer individuals of both species.