If this is all the time a pest control service is spending, their efforts will fail. German cockroach problems may persist despite careful pest control efforts, Gold says. In some areas, they have become resistant to particular insecticides. In recent years, German roaches in some regions seem to have become resistant to nearly all insecticides. Resistance to boric acid has not been noted to date.
Gold recommends that people use a licensed and certified pest control operator whenever possible.
The average homeowner is very reliant on pesticides. For more information on insecticides, please see Extension publication B-1373 from your local county Extension office.