I think you now have to build that piece behind/over it 
I know, what a labour that'll be...

How long will it take for the bugs to get through them?
Maybe a plasma bug strike? I was thinking more having them jammed and being stuck on the outside with the hordes of bugs.
In their current form, I'm afraid the bugs would just step 10' to the side and run around them...not much good I'm afraid. 
Damn a flaw! Fits in with aliens getting through the suspended ceiling though...