It is a triangular trap, made of plastic or water proof card. Insects that attracted, depending upon the pheromone lures, fly into the trap and stick to the surface coated with a special type of non-drying glue.
Wax coated cardboard (shape to be made as per image)
Small piece of wire for suspension
Take a hard waterproof cardboard sheet of 18 x 9 inches. Make folding marks to make delta shape and staple the loose ends. Paste glue material in the inner side of trap. Hang the bait/lure from the holes from the top. Use wire/rope for hanging the trap close to the plant canopy. Change the lures once in 15-20 days