The H-trap controls horsefly numbers and is designed to be placed outdoors. The shape is designed to mimic an ideal target for female (the ones that bite) horseflies. The insects are ‘tricked’ into mistaking the trap as a large animal.
They are attracted to the heat from the large black ball. Once they land on the black ball, they will try to bite it and when they fail to obtain a blood feed, they fly upwards, where they are caught in the funnel and guided into a centrally placed collection bin.