Cockroaches appear in warmer weather. They are attracted to food that is left out, crumbs on the floor, and moisture, e.g. from leaking pipes and taps. They can carry pathogens and can infect your food, e.g. with E. Coli and salmonella, so don’t take an infestation lightly.
You’ll need to cut off their food supply by cleaning up any leftover or spilled food, checking the back of cupboards, behind the refrigerator etc. Combined with a baiting program this usually eliminates the cockroaches.