She is probably used to them in her own country.
Get in Pest control 04 268 7600 as piff paff will not be sufficient to deal with the number you have referred to of those creatures.
Train and retrain you maid in the manner you require.
Good luck
Over Christmas i gave my maid a week off and had to enter her room which is in the house. The room was crawling with cockroaches, so sprayed enough piff paff to knock out most of Mirdiff. I never enter her room, but when she came back (i left the gazillion corpses on her floor as a HINT) and asked her to clean her room well she just shrugged. She seems oblivious to them being a problem. How do i get her to understand she needs to be cleaner and more careful with her food?