Three days ago, I put Frontline Plus on Max. Yesterday, I found two engorged ticks. Are the ticks supposed to fall off after the Frontline application, or does it just prevent more ticks from attaching?

I'm wondering if I need to apply more. It says to only do it once every 30 days, so I'm hesitant to reapply it. However, it was left over from last year and I'm wondering if it's not working because it was old.

Any knowledge you can share?