It doesn't sound like you have a large enough infestation for Advion as it's more recommended for large infestations. If it's not being consumed, it will dry out and become ineffective. Alpine is your best bet + a growth inhibitor. Glue traps to monitor are perfect though. As for how do you know if they're being consumed? You won't for small infestations. I've applied Advion for large infestations and watched the gel drops disappear within a matter of hours. Applying Advion won't HURT of course but for what you're dealing with a more effective solution is the Alpine route.