German cockroaches favor warm, humid spaces near food and water — kitchens, behind appliances, under sinks — and Western Springs's a climate shaped by proximity to Lake Michigan, with colder, snowier conditions than much of downstate Illinois keeps them active most of the year. American cockroaches, larger and reddish-brown, prefer basements, drains, and utility rooms. Historic brick two- and three-flat buildings make up much of the older city housing stock, alongside postwar suburban tract homes.
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.