Evaluation of attractants in traps for greenhead fly (Diptera: Tabanidae) collections on a Cape Cod, Massachusetts, salt marsh

Field studies evaluated 1-octen-3-ol (octenol), carbon dioxide (dry ice), and a combination of both attractants in comparison with unbaited traps for collecting greenhead flies on a Massachusetts salt marsh. The carbon dioxide (CO2)-baited trap collections, and the CO2 with octenol-baited trap collections were more than 300% greater than the unbaited collections. The octenol-baited traps collected 83% more greenhead flies than unbaited traps. Afternoon trap collections were 2.5 times greater than morning collections. Dissections and measurements of a sample of the flies collected indicated that the cryptic species composition of greenhead flies was 77% Tabanus nigrovittatus and 23% Tabanus conterminus. Ovarian tracheole examinations of a sample of the flies showed that 99% of the greenhead flies had laid eggs before being trapped. The use of CO2 as an attractant in the traps could be cost effective in small problem areas, and the use of octenol in the box traps should be evaluated in large areas.