German cockroaches favor warm, humid spaces near food and water — kitchens, behind appliances, under sinks — and Markham'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.
We start with an inspection to identify the species and the source — sanitation issue, moisture problem, or entry point. Treatment centers on gel bait placed in cracks, voids, and under appliances, not broadcast spraying, since German cockroaches in particular have developed resistance to many surface sprays. A follow-up visit confirms the bait is working and the population is dropping.