Bed bugs are small, nocturnal insects that feed on the blood of humans and animals. These pests are a common concern in homes and while traveling, often leading to questions about why some individuals appear to be bitten more frequently or react differently to bites. Understanding the factors that draw bed bugs and the varied human responses to their bites can help address these observations.
Factors That Attract Bed Bugs
Bed bugs rely on specific cues to locate a host. Carbon dioxide (CO2) is a significant attractant; humans exhale CO2, creating a plume that bed bugs can detect from a distance, guiding them toward a potential food source. Bed bugs are highly sensitive to CO2, using it as a primary signal, especially at night when humans are at rest and CO2 levels are concentrated.
Body heat also plays a role. These insects are drawn to warmth, specifically temperatures between 70-80°F, similar to human skin temperature. Their thermal sensors allow them to detect heat from several feet away, leading them to exposed skin.
Certain skin chemicals and volatile compounds, such as those in sweat, also draw bed bugs. Lactic acid, a component of sweat, is particularly attractive as it signals the presence of human blood. Dirty laundry containing lingering human scents like sweat and skin cells can also attract bed bugs, mimicking a host’s presence. While blood type is sometimes discussed, current scientific consensus does not strongly support it as a primary factor; bed bugs are generally opportunistic feeders.
Why Bite Reactions Differ
Even when multiple individuals are bitten by bed bugs, visible reactions can vary significantly. This variability stems from the human immunological response to compounds in the bed bug’s saliva. Some people may develop noticeable red, itchy welts, which can be flat or raised bumps, sometimes appearing in lines or zigzag patterns on exposed skin. These reactions are a localized allergic response to proteins in the insect’s saliva.
For other individuals, there might be no visible reaction at all, even after repeated bites. This lack of reaction can lead people to believe they were not bitten, making infestations harder to detect. In some cases, reactions may be delayed, appearing several days after the bite. More severe reactions, though rare, can include larger swollen welts, fluid-filled blisters, hives, or systemic symptoms like difficulty breathing. The intensity of the reaction can also change over time, with some individuals becoming more sensitive with repeated exposure.
Reducing Bed Bug Encounters
Understanding what attracts bed bugs can inform strategies to minimize encounters. When traveling, inspect hotel rooms for signs of bed bugs, focusing on mattresses, headboards, and upholstered furniture. Placing luggage on hard, elevated surfaces, such as metal luggage racks, instead of the floor or bed, can help prevent bed bugs from hitchhiking. Using hard-cased luggage and packing clothes in re-sealable plastic bags can also create barriers.
Upon returning home, unpack luggage in a garage or utility room rather than the bedroom. Immediately wash all clothing in hot water and dry them on the highest heat setting for at least 20 minutes, as heat kills bed bugs. For items that cannot be washed, consider placing them in a sealed bag in a sunny area. Using mattress and box spring encasements that are bed bug-proof and seal tightly can help prevent bed bugs from infesting these areas or trap existing ones. Regular vacuuming, particularly around sleeping areas, and reducing clutter can also limit hiding spots for bed bugs.