Ant bait and ant spray solve different parts of the problem.
Spray can knock down exposed ants quickly. Bait uses normal foraging behaviour so workers can carry treatment through more of the colony. The right choice depends on what you are trying to achieve.
If you are using bait, avoid spraying the same trail unless the product labels clearly allow it. Worker ants need to reach and feed on the bait.
Spray gives visible knockdown
A contact spray can kill exposed ants and treat labelled surfaces. The nest or satellite colonies can remain active somewhere else.
Bait uses the trail instead of breaking it immediately
Workers feed on or carry bait and move it through the colony. That takes time and depends on the bait being accepted.
Food can compete with the bait
Sugar, grease, pet food and rubbish can pull ants away from a bait placement. Cleaning the surrounding area helps remove competing food.
Species can change the result
Ghost ants, pharaoh ants and other household ants differ in nesting and food preference. When one method repeatedly fails, identification can be more useful than applying more product.
What people usually want to know
Is ant bait better than spray?
They do different jobs. Bait is often chosen when the aim is to reach more of a colony; spray can provide quick control of exposed ants.
Can I use bait and spray together?
Only when the product labels support that use and the spray will not repel ants from the bait area.
Why are there more ants around the bait at first?
Bait can draw foraging ants to the placement. More feeding at the bait does not automatically mean the infestation suddenly became larger.