[Shop-talk] Eradicating yellowjackets in a stone wall?

[Jim Franklin]

I tried to kill a yellowjacket nest in a stone wall tonight. They are entering at ground level. Any experienced opinions on where I should have aimed the can? I only had one  :-)  Emptied 3/4 of it into the gap in the wall but not a single angry wasp came out so I'm not convinced I hit anything. Morning will tell. 

Should I expect they're in the ground, or would they have built a nest amongst the rocks? I've never seen that.

(fire, nukes, pros, all not viable options at the moment)

If the can didn't work, any ideas on what to try next?

thanks,
jim