Influence of trap screen age on collections of Tabanids in Malaise traps

Since natural-colour Saran gauze darkens with age, Malaise traps constructed of this screen and of different ages were compared to determine if there was an effect on collection numbers due to ageing. In addition, a trap constructed of black polypropylene gauze and a Saran gauze trap painted with black enamel were included in this study. The data showed a significant reduction in the numbers of Tabanids collected associated with an increase in trap age. In the new traps were collected about 5 times as many Tabanids as in the black ones. This drop in numbers collected, which may be related to light intensity within the trap, should be considered when such traps are used in critical studies.