Cockroaches are attracted to food, moisture, shelter, and warmness. They are attracted to the moisture like leaky pipe underneath the bathroom sink, wet bathmat lying on the floor. Mainly the cockroaches are attracted to the food that has been left at places like kitchen counter, dirty dishes, crumbs of food laying on the floor. These insects lay their eggs at the location where they found appreciable amount of food which can support their lives.
Thus the spoiled food in the refrigerator is the source of growth and infestation of the cockroaches.
