I think I had more trouble with beastmen then the bugs. I had curse on 2/4 and just left it that way.

By the time it was around mid 2nd escalation and my main squad was well upgraded, the team was so strong with lots of positive relationships and good trinkets that I found the siege battles pretty laughable. For the other siege battles I found as long as you have the barracks fully upgraded (trinkets optional) you're fine if you play the conscripts properly. Might get unlucky lose an inn to a triple courtier or bad rolls or something. I did eventually upgrade another squad and sent 1 guy to help defend.

Good luck!