i would just remove the water feeder
You could do, but they probably just dig them selfs in deeper, in to the sand. :)
Not a bad idea Badman.. I might have to try that.. It wouldnt worry me if they dug in deeper Jimmy.. just worries me they wont have water lol..
UPDATE:
Ok i did try that.. they didnt seem to happy... but went under the ytong block.. Then around 20 mins ago i thought id have a look n check on them.. n in amazment i see around 20-30 workers running over the lid.. down the tank and across my desk into a pack of moos lol.. BLOODY Mental... So... Moos ball now in tank.. PTFE on the tank.. and Vaseline around the eges on the bungs.. and i also noticed they have have nested up against the side of the ytong.. so i can still see them lol.. Pretty mad..