Is'nt there an electronic product that makes noise on your electrical wiring that annoys rodents and bugs?
Yep, but I'm by default highly skeptical of these things...
i dare ya to try it out on the infestation nad then do a full product report. <sillyness>Think of the money to be made monetizing a page on roach repellents for NZ </sillyness>
It does occur to me - huhu grubs are a delicious native NZ treat. If these roaches are Nz native maybe there is a buck to be made frying or BBQ'ing them and selling them to tourists. NZ's version of cricket on a stick.