Large scale use of box traps to study and control saltmarsh greenhead flies (Diptera: Tabanidae) on Cape Cod, Massachusetts

During May and June in 1970-79, about 300-730 box traps painted with light or dark colours were placed around the perimeters of Cape Cod salt marshes in Massachusetts to capture adults of Tabanus lineola F. and T. nigrovittatus Macq., which emerge during July and August. Yearly fluctuations in the average counts from a sample of 33 box traps visited weekly, generally correlated with average counts from unpainted, adhesive-smeared, square, masonite traps located at 6 sites in experimental marshes and 2 sites in control marshes. These data and annual counts from about 40 additional box traps indicated that trap catches were related to annual variations in tabanid populations, marsh size, random movement of flies and weather conditions rather than to the box trap colour. Over the 10-year period, a noticeable and measurable decrease in the nuisance level of the flies occurred around the perimeters of all marshes containing box traps. Samples of Tabanus taken from the traps were identified as 95.9% females of T. nigrovittatus, 3.6% females of T. lineola, 0.4% males of T. lineola and small numbers of females of T. atratus F., males of T. nigrovittatus and other Tabanus spp. None of the trapped females that were killed and examined internally contained blood in the digestive tract, and almost 100% were parous. A list of other insects found in the box traps is given.