The Gumtree Delta Trap has three components – the outer covering or the trap, a Gumtree sticky liner, and a pheromone lure (not sold by Gumtree but available in the market from other manufacturers). The pheromone lure emits odors that attract the target insect pests. When the pheromone lure attracts the insects to get into the Delta trap, they get stuck on the sticky liner. A count of the insects trapped on the sticky liner indicates the pest population.