How does a monarch butterfly help the ecosystem?

Some negative impacts people put on monarchs are that when they go to hibernate some trucks can kill them when they are going over the road. Another thing is that some people go off and try to kill these beautiful butterflies some people also try and mess with them when they are in there canoe and trying to form into a butterfly and that can affect how the monarch will turn out so that is another negative thing that people impact on beautiful monarchs.