Cockroaches are omnivorous insects with a wide range of food options. They like all kinds of flour products, melons and fruits, and are especially fond of fragrant, sweet and oily foods. Some even refer to them as "oil thieves" because they are very interested in sesame oil. In addition, brown sugar and caramel are also very attractive to cockroaches.
In addition to food, cockroaches also eat other items. In their homes, warehouses and storage rooms, they may nibble on cotton goods, leather goods, paper, books, and even soap. Outdoors in places like garbage dumps, sewers, and toilets, cockroaches feed on putrefactive organic matter and can even gnaw on dead animals. Different species of cockroaches also have different food preferences, for example, the German cockroach likes fermented foods, the black-breasted cockroach likes sugar and starch, the American cockroach likes spoilage substances, but also has a strong attraction to sugar, and the Australian cockroach likes plant food.
Water is also essential for the survival and development of cockroaches. For example, in the 1st instar nymph stage of the brown spotted cockroach, even if there is no food, as long as there is a water source, it can have 227% of larvae successfully develop into 2nd instar. However, they cannot grow and develop without water**. Cockroaches are able to endure hunger but not thirst, for example, in the case of providing only dry food but no water, the female of the American cockroach can only live for 40 days and the male can only live for 27 days. Conversely, if there is only water and no food, the female can live for 90 days and the male can live for 43 days.
In harsh environmental conditions, without food and without water, cockroaches may eat each other. They compete for food resources, especially for freshly shed larvae, and their immobile and tender epidermis make them the object of competition for food. 
It is important to note that cockroaches have a wide range of activities and can contaminate and swallow large amounts of pathogens. This, combined with the fact that they may spit out and excrete waste while eating, makes them mechanical transmitters of pathogens.