I have a 2 year old house in south georgia, usa. A friend says I should
caulk the joint between the bottom of the exterior siding and the concrete
slab to prevent insects from nesting in the wall. Makes sense but I am
reluctant because I thought the joint should be open to allow moisture to
escape.

Should i caulk up this joint? Also is it better to use caulk or foam?

Thanks
Scott