To keep squirrels from inhabiting the space under a shed in the back yard I blocked off the openings with hardware cloth. The bottom is buried in a trench to keep them from digging under. I finished Sunday morning. Sunday afternoon we are sitting outside enjoying the nice weather. Two squirrel chasers are with us. A squirrel ran into the yard, in sight of the dogs, only to find her access to the safe space blocked. The dogs thought it was their lucky day and squirrel fever ensued, but they were not quick enough.