General spraying may kill a few ants but the bulk will not have been touched and will carefully circumvent the sprayed area and pester you in another spot. To locate ant nests, put down a tiny amount of sugar and wait. Soon the ants will have formed a living path from the sugar to the nest. Ants do not like Ajax. You can rid any working area of them for a while by wiping liberally with Ajax and not removing all of it.
Ammonia takes the itch out of bites.
If you find ants crawling over clean dishes in the cupboard, you may conclude that an imperceptible film of grease remains on the dishes. Make sure that your dishes will not be damaged by the concentration. For cockroaches, spraying can be effective. Concentrate especially on crevices in wood where eggs tend to be deposited. Cockroaches live in the soil under the houses, around water and sewage pipes, in cesspools, etc.