Cockroaches are omnivorous scavengers that eat nearly anything organic. Their preferred foods are sweets, starches, and meats, but they’ll readily consume hair, paper, soap, glue, decaying matter, and even each other when options run thin. This extreme dietary flexibility is a big part of why they’ve thrived alongside humans for millions of years.
Preferred Foods
Given a choice, cockroaches gravitate toward sugary and starchy foods first. Crumbs, grease, fruit, cereal, baked goods, and meat scraps are all high-value targets. In laboratory studies, developing cockroaches consistently self-select a diet with roughly two to three times more carbohydrates than protein. That ratio shifts in real-world conditions: cockroaches collected from apartments chose significantly more protein-rich foods than lab-raised colonies, likely because wild roaches need to compensate for less predictable nutrition.
Pet food left in bowls overnight, grease residue on stovetops, and crumbs under appliances are some of the most common food sources in homes. Cockroaches feed mostly at night, so these remnants can sustain a population without anyone noticing.
Non-Food Items They Consume
What makes cockroaches especially hard to starve out is their ability to eat things you’d never think of as food. They routinely consume:
- Paper and cardboard: book bindings, wallpaper paste, newspaper, and shipping boxes
- Fabric and leather: especially items stained with food or sweat
- Soap and toothpaste: residue in bathrooms is enough to sustain them
- Hair and fingernail clippings: keratin is digestible for them
- Dead skin flakes: human dander accumulates in bedding and carpets
- Glue: including the adhesive on stamps, envelopes, and wallpaper
- Wood: species living on dead trees consume decaying wood directly
This list explains why even spotless-looking homes can still support cockroaches. A bathroom with soap scum, a bookshelf with old paperbacks, or a pile of cardboard in the garage all qualify as food sources.
How They Digest Almost Anything
Cockroaches pull off this dietary versatility thanks to a dense community of gut bacteria. Their hindgut houses specialized microbes, particularly from a group called Bacteroidota, that produce large quantities of enzymes capable of breaking down complex plant-based materials. These enzymes can dismantle xylan (found in wood and cereal grains) and other tough carbohydrate structures into simple sugars the cockroach absorbs.
Some of these gut bacteria even produce structures called cellulosomes, molecular machines specifically designed to break apart cellulose, the structural fiber in wood, paper, and cardboard. This means a cockroach chewing on a cereal box isn’t just gnawing aimlessly. It’s actually extracting usable calories from the material. The bacterial community also ferments amino acids and produces short-chain fatty acids, giving cockroaches nutritional value from sources that would be worthless to most other animals.
Cannibalism and Feces as Food
When conventional food runs low, cockroach colonies don’t just tolerate desperate measures. They rely on them. Coprophagy (eating feces) is a normal and well-documented behavior, especially among young nymphs. First-stage nymphs that can’t venture far from the shelter eat adult feces as a primary food source. In lab conditions, starved nymphs ingested roughly three times more fecal material by weight than they would normally eat in solid food over the same period.
The behavior scales with need. When food was placed far from the shelter, young nymphs ate nearly three times more feces than when food was nearby. This isn’t a quirk. It’s a survival strategy that also transfers gut bacteria from adults to offspring, seeding the digestive community the young cockroaches need to process tough foods later in life.
Cannibalism and necrophagy (feeding on dead roaches) also occur, particularly among slightly older nymphs that can move around more freely. Under crowded or food-stressed conditions, dead or weakened individuals become a protein source for the rest of the colony.
Diet Differences by Species
The species you’re dealing with affects what they’re eating in your home. German cockroaches, the most common indoor pest worldwide, are true generalist omnivores that thrive on kitchen scraps, grease, and starchy residues. They tend to stay close to food and water sources, which is why they cluster in kitchens and bathrooms.
American cockroaches are larger and more likely to feed on decaying organic matter. Those living in sewer systems feed directly on sewage. When they enter homes, they favor fermenting fruit, damp paper products, and pet food. Oriental cockroaches share that preference for decaying material and are often found feeding on garbage and leaf litter. Brown-banded cockroaches are slightly different: they’re more likely to be found away from kitchens, feeding on starchy items like wallpaper glue, book bindings, and the sizing on older fabrics.
How Long They Survive Without Food
A cockroach can survive about one month without eating. Being cold-blooded, their metabolic rate is low enough that stored energy lasts a long time. Water is the real bottleneck. Without it, most cockroaches die within a week, which is why they congregate in humid spaces like bathrooms, basements, and around leaking pipes. Eliminating moisture sources is often more effective than eliminating food sources alone.
Cutting Off Their Food Supply
Because cockroaches can eat so many things, sanitation has to go beyond wiping counters. Store loose food in tight-fitting containers. Clean up spills and food waste immediately, and don’t leave unwashed dishes or pet food bowls out overnight. Take garbage out regularly rather than letting it accumulate.
The less obvious step is removing the non-food sources. Stacks of paper bags, old newspapers, and cardboard boxes are all cockroach meals waiting to happen. The University of Kentucky’s entomology department recommends either discarding these items or storing them in sealed plastic bags. Reducing clutter in humid areas like basements is particularly important, since it eliminates both food and shelter at the same time.