German cockroaches favor warm, humid spaces near food and water — kitchens, behind appliances, under sinks — and Columbus Junction's a humid continental climate with hot, humid summers and cold winters, somewhat more humid than western Iowa given the Mississippi River's influence keeps them active most of the year. American cockroaches, larger and reddish-brown, prefer basements, drains, and utility rooms. A blend of established manufacturing-era neighborhoods and newer suburban growth along the Mississippi River corridor.
Treatment starts with locating the harborage points — the tight, warm, food-adjacent spaces roaches actually live in — and applying gel bait directly there rather than spraying open floor space. This targets the colony at its source and avoids the resistance issues that plague over-the-counter sprays. We follow up to verify the population has collapsed, not just scattered.