i get this too, and in fact, any place where the ground is bare, they come in droves. the worst time for me is the spring, though, i noticed this weekend it has infested the border of my vinca minor.

this year i was planning on trying to use some pre-emergent...hit it a few times. i am particularly worried about this as i am in the middle of putting in a ground cover of liriope -- but i will use wood mulch to help the ground retain moisture until the liriope takes over.