Brown marmorated stink bugs (BMSB) have become a common household nuisance, especially as cooler weather approaches. They seek refuge indoors. Understanding how temperature influences their survival is important for managing their populations effectively.
Understanding Stink Bug Temperature Tolerance
Stink bugs are ectothermic, meaning their body temperature is directly influenced by the environment. Brown marmorated stink bugs thrive in a moderate temperature range, with optimal conditions typically observed between 25 and 30 degrees Celsius (77 to 86 degrees Fahrenheit). As temperatures drop in late summer and fall, these insects instinctively search for protected overwintering sites, often invading homes. During this overwintering period, known as diapause, their metabolism significantly slows; they do not feed or reproduce. They remain inactive until warmer temperatures signal their emergence, which can sometimes occur during unseasonably warm spells.
Lethal Cold Temperatures
Stink bugs are considered “chill-intolerant,” meaning they succumb to the cold before their internal body fluids actually freeze. Their supercooling point, the temperature at which their bodily fluids would freeze, typically ranges from approximately -12.6 to -16.93 degrees Celsius (9.3 to 1.5 degrees Fahrenheit). However, mortality occurs at temperatures well above this point due to physiological stress. Exposure to cold temperatures between -10 and -15 degrees Celsius (14 to 5 degrees Fahrenheit) can lead to a significant drop in survival rates, ranging from 73% to 86% in populations.
For example, sustained temperatures of 23 degrees Fahrenheit (-5 degrees Celsius) can kill 50% of a stink bug population within four hours, and 90% within seven hours. At slightly warmer temperatures, such as 32 degrees Fahrenheit (0 degrees Celsius), it takes about a week of continuous exposure to achieve 95% mortality. Extreme cold events, like those experienced during a Polar Vortex, have been observed to cause mortality rates as high as 95% to 98% in exposed stink bug populations. When temperatures fluctuate during winter, causing brief warm spells, stink bugs may become active, depleting their energy reserves and making them more vulnerable to subsequent cold snaps.
Lethal Hot Temperatures
Stink bugs are also vulnerable to high temperatures, with specific thresholds. Complete mortality occurs after just 10 minutes of exposure to 50 degrees Celsius (122 degrees Fahrenheit). At 47.5 degrees Celsius (117.5 degrees Fahrenheit), 100% mortality occurs within 15 to 20 minutes, and prolonged exposure to 45 degrees Celsius (113 degrees Fahrenheit) for one hour or more is also lethal to adults.
Even at lower elevated temperatures, significant mortality can occur; for instance, 91% to 100% mortality has been observed after four hours at 42 degrees Celsius (107.6 degrees Fahrenheit). Temperatures above 40 degrees Celsius (104 degrees Fahrenheit) are particularly critical for these physiological disruptions.
Using Temperature for Stink Bug Control
Understanding the lethal temperature ranges for stink bugs provides practical methods for their control. Homeowners can leverage cold temperatures by collecting stink bugs and placing them in a sealed bag or container, then transferring them to a freezer. Sustained exposure to freezing temperatures, or 0 degrees Celsius (32 degrees Fahrenheit) for about a week, will effectively eliminate them. This method is generally safe and minimizes the release of their defensive odor.
Heat can also be used as a control measure, though with more caution. Steam cleaners can be effective for directly applying lethal heat to stink bugs hiding in cracks, crevices, or around window frames. Alternatively, a sealed container or vacuum bag containing collected stink bugs can be placed in direct sunlight on a hot day, such as inside a vehicle, where temperatures can quickly reach lethal levels. When using heat-based methods, it is important to consider the materials and surfaces involved to avoid damage.