Domestic cockroaches and mice often bite or nibble on food packages. Bite marks on paper, plastic bags or almonds were studied under laboratory conditions. Polyethylene film was torn off by bites of large cockroaches (Periplaneta fuliginosa, P. americana or P. brunnea) and resulted in crater-like holes or crevices on the surface. The German cockroach could not tear off plastic film. The vinylidene-polychloride films (wrap film) were also cut by all species, including B. germanica, but the edges of holes did not appear to be so raised as those of polyethylene film. The mice made small round bite holes on the surface of polyethylene films, but the edges were not raised up. They also fragmented the wrap films in small pieces. The large cockroaches brought together fibers of Kraft paper or Japanese paper (Washi). The German cockroach bit off saw-tooth patterns at the edges of the papers. However, no holes appeared on the surface. The mice gnawed off the paper. The large cockroaches nibbled on almonds and imprints of their mandibles were clearly visible where they nibbled. The German cockroach ate only the insides of rinds. The cockroach and mouse bite marks in almonds were not similar.

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Food preference in nine cockroach species (the German cockroach, Blattella germanica, the smoky brown cockroach, Periplaneta fuliginosa, the Japanese cockroach, P. japonica, the brown cockroach, P. brunnea the American cockroach, P. americana, the Satsuma cockroach, Opistoplatia orientaris, the lobster cockroach, Nauphoeta cinerea, the blaberus cockroach, Blaberus trapezoideus and the Madagascar cockroach, Gromphadorrhina portentosa) was studied under laboratory conditions. Adults of each species were released for 72 hours in an arena and fed seven different kinds of powdered food materials, rice bran, mouse food, wheat flour, dry yeast, dried sardine, dried Shiitake and green tea. Food materials were set around the circumference at regular intervals in a small plastic cup. The consumption rate of each food was checked. Six species (German, American, Brown, Lobster, Blaberus and Madagascar) preferred the rice bran most. However, rice bran consumption by the Japanese cockroach was only 10% of the total, and this species accounted for 44.8% of the total dry yeast consumption. Mouse food was selected most by the smoky brown and the Satsuma. Dried Shiitake was selected by only the Madagascar (14.5%), and green tea was consumed by the Japanese (15.3%) while other species consumed only a little. Dry yeast was consumed moderately by the American (25.7%), the brown (21.5%) and the smoky brown (19.7%). The feeding patterns of the American and the brown were very similar. The large cockroaches consumed more food materials than did smaller ones.

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