Samll brown worms with legs have shhownup on my screened in porch and my front porch they crwl up in a coil whe I kill them how do I get rid of them

That's a common description of millipedes. There are lots of species worldwide. Look:

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The best thing to do to get rid of them is to dry up the areas around your porches. Gardners say if it's wet enough for bugs it's too wet for plants. Mulch should be turned if not removed, drainage from a/c units should be directed away from the building, and rainfall runoff should also be redirected.

If you wish to use a pesticide, the lawn and garden stores sell many types of granular insecticides that will work as well as anything on these creatures. Liquid sprays will only make the problem worse as they add more moisture to an already wet environment.