The efficacy of alphacypermethrin-treated high density polyethylene (HDPE) mesh appliedto jet stalls against Culicoides biting midges (Diptera: Ceratopogonidae) was determined bymechanical aspiration of midges from horses and using Onderstepoort 220 V downdraughtblack light traps in four blocks of a 3 × 2 randomised design under South African fieldconditions. The alphacypermethrin-treated HDPE mesh applied to the stall significantly(P = 0.008) reduced the number of Culicoides midges, predominantly Culicoides (Avaritia)imicola Kieffer, mechanically aspirated from horses housed in the stall. The mesh reducedthe Culicoides midge attack rate in the treated stall compared to the untreated stall and asentinel horse by 6 times and 14 times, respectively. The number of Culicoides midges andC. imicola collected in light traps from the untreated and alphacypermethrin HDPE mesh-treated stalls did not differ significantly (P = 0.82). Alphacypermethrin-treated HDPE meshcould be used to reduce exposure of horses in jet stalls to Culicoides midges, specifically C.imicola, and the risk of midge-borne Orbivirus transmission.