The Food Safety and Inspection Service office in Alameda, Calif., sent a letter to Foster Farms Chief Executive Officer Ron Foster saying inspectors had found cockroaches inside the Livingston plant in the northern San Jaoquin Valley five times from Sept. 14 though Jan. 9.
During the latest inspection on Wednesday, cockroaches were found at a hand-washing sink.
Foster Farms temporarily suspended operations for "enhanced sanitizing," but said only five cockroaches had been found at the facility over the past four months and that no chicken products were affected, the Modesto (Calif.) Bee reported.
"This action is initiated based on egregious insanitary conditions observed in your establishment whereby products at your facility may have been rendered adulterated by violation of the Poultry Products Inspection Act," the FSIS letter said.
The U.S. Department of Agriculture has not recalled any Foster Farms products.
In October, FSIS threatened to temporarily close the same plant and two Foster Farms operations in Fresno because of salmonella contamination.