Cockroaches eat on anything - almost.

Dr Abe V Rotor 

True. Being omnivorous, cockroaches voraciously consume all kinds of materials that are rich in carbohydrates, proteins, fats and oils.  But when these are not available they turn to unlikely food source like soap, photographic film, clothes, wood and drugs.  In fact they even turn into predators, devouring other insects, and sometimes biting people in their sleep. Their bite often gets swollen and infected. Cockroaches are found in all places where humans live and conduct his trade, commerce and industry. Only rats can be compared with the tenacity of the cockroach.    

American cockroach (Periplaneta Americana)

The cockroach has very powerful digestive enzymes:  proteases digest protein, invertase breaks complex sugar, and amylase breaks starches.  Its saliva contains powerful enzymes coming from the gastric caeca, while the Malphigian tubules secrete an enzyme that is equally disgusting.  It is no wonder that just a single frass (feces) can spoil a whole pot of rice by its obnoxious smell. By the way there are three most common species that we encounter in the home and public places.  These are the American cockroach or Periplaneta americana (large, rust red with a yellow band across its thorax), the German cockroach or Blatta germanica (pale yellow, only one-third the size of the American species) and the oriental cockroach or Blatta orientalis (dark brown to black, the biggest and filthiest of all cockroaches.)

Meticulous sanitation is the best way to get rid of cockroaches. To keep their population down, sprinkle carbamate (Sevin) on the kitchen floor, pathways and possible hideout of the pest, preferably before retiring at night.  Keep doors and screens properly closed to prevent entry of the insect.