Magiclantern's Frink said :Bingo, what would/did you do with an ant or termite infestation?

I have explained this in the TLDR post above.

With ants I found a natural solution to the problem in the form of covering the doorsteps with eucalyptus oil. Ants navigate via smell and will avoid going places with certain aromas and it worked perfectly.

The tiny brick spider problem however we had to get an exterminator in because they couldn't be moved and would have brought our house and presumably the neighbour's house down too.

I wasn't happy about it though.