Wow, Jewelweed mulch and no slugs

I picked 2 dozen slugs off 9 unmulched but extravagantly hilled potato vines and zero off the adjacent 30 mulched with jewelweed.
Does this call for a repellant foliar spray experiment or does mulch routinely deter these pests?

Wow Burl....nice observation!  May the observations continue!!!  I have lots of slugs, and lots of jewelweed.  I'll start paying very close attention now and add my observations in as well.  I frequently pull it out and lay it down or else it would shade out many of my plants.  Maybe I've accidentally done a good mulch job in a few places?  This would be an amazing tool for me if it works.

Since I adopted no dig and straw mulch I have had barely any slugs. Voles on  the other hand.....

I could assume that my slugs have a taste for the extravagant and are hiding under the mulch.