I run about 3 times a week, and typically log 10 miles. This is less than I should be, but it's summer and I'm getting slacky.

I was just wondering, when I'm on I log about 15-20 miles a week and I run about a 10 minute mile... Should I be working on my thighs and calves with weights? I figure if running isn't doing it (as well as working as my cardio), I need to know WHAT specifically running misses and HOW, specifically, to target those muscles.
Thank you much!
Kaitlin.