Effective bed bug (Cimex lectularius L.) monitors have been actively sought in the past few years to help detect bed bugs and measure the effectiveness of treatments. Most of the available active monitors are either expensive or ineffective. We designed a simple and affordable active bed bug monitor that uses sugar—yeast fermentation and an experimental chemical lure to detect bed bugs. The sugar—yeast mixture released carbon dioxide at a similar rate (average 405.1ml/min) as dry ice (average 397.0ml/min) during the first 8 h after activation. In naturally infested apartments, the sugar—yeast monitor containing an experimental chemical lure (nonanal, L-lactic acid, 1-octen-3-ol, and spearmint oil) was equally effective as the dry ice monitor containing the same lure in trapping bed bugs. Placing one sugar—yeast monitor per apartment for 1-d was equally effective as 11-d placement of 6–18 Climbup insect interceptors (a commonly used bed bug monitor) under furniture legs for trapping bed bugs.When carbon dioxide was present, pair-wise comparisons showed the experimental lure increased trap catch by 7.2 times. This sugar—yeast monitor with a chemical lure is an affordable and effective tool for monitoring bed bugs. This monitor is especially useful for monitoring bed bugs where a human host is not present.