information about Exterminator in Thailand

Who is familiar with exterminators in Thailand? Specifically how often do they come around? Inside and outside? What are the health implications especially around small children?

My rental contract includes once a month. I haven't seen them doing it but heard they spray inside the house along floor skirts. My wife usually hides all our sons toys and things he might take in his mouth and leaves the house for 3-4hours.

And btw... Merry Xmas