first Cut the top off a plastic bottle to make a funnel. Then turn the funnel up-side-down so it fits inside the container. this will make it a easy to enter but not to leave. Then add a blend of vinegar, sugar and salt.
Keep the trap out of the rain or it will quickly fill with rain water.
Warning : This trap will likely attracts and traps helpful insects such as lacewing and hoverflies which are a natural pest control of aphids.