I did an image search on Google with you picture and got this

horsefly trap, also known as a cleg trap or MT-Trap. Purpose and Function The trap is designed to effectively reduce the population of biting insects like horseflies (cleggs) and wasps in outdoor areas without the use of chemicals or electricity. It is ideal for use near paddocks, stables, gardens, terraces, and golf courses. How it Works Attraction: Sunlight heats the large, black plastic ball, which hangs under the conical screen. The heat and movement in the wind simulate a large animal (a prey animal), attracting the blood-sucking female horseflies. Capture: When the insect lands on the ball and attempts to bite, it realizes its mistake. Their natural reaction is to fly upwards towards the light. Containment: Instead of flying away, they are guided into the green cone-shaped funnel and up into a collection container at the top, where they are trapped and die. Independent trials have shown that these traps can reduce the number of horseflies by up to 90-95% in an area of approximately 10,000m².