The Effects of Cold Weather on Roaches
Cockroaches don't typically function well in cold weather, but they've developed defense mechanisms that help them to survive when temperatures fall.
Cockroaches in the Garden
Most species of cockroaches common in the United States prefer consistently warm temperatures and, therefore, tend to infest indoor spaces rather than gardens. Some species, however, such as the Pennsylvania wood cockroach, may live under logs or in other dark, damp outdoor spaces, and other species, such as the Oriental cockroach, can survive outdoors even when temperatures fall below freezing. When the weather gets cold, though, these species may move from the garden into the home in search of warmer temperatures, and in sheltered areas, they may be able to survive outdoors.
Temperatures and Survival
Because they're adapted to survive in warm temperatures, and because they're cold-blooded organisms that can't regulate their own internal body temperatures, cockroaches can't survive if their environment is either too hot or too cold. Most species' members die when they're exposed to temperatures above about 115 or below 0 degrees Fahrenheit for a prolonged period of time. Consequently, most roaches, especially subtropical species such as the Australian and Surinam cockroaches, are unlikely to survive in gardens in areas with cold winters.
Falling temperatures may limit roaches' activity, and they may stop growing and reproducing when exposed to temperatures below 45 degrees for a long period of time.
Roaches, however, may be able to adapt to cold temperatures when they're exposed to them gradually. Oriental cockroaches, for example, have been shown to be able to survive considerably longer in subfreezing temperatures when first subjected to a cool-temperature acclimation period.
Roaches' physiological responses to cold temperatures may be enough to keep them alive even when temperatures are very low, assuming the temperature drops gradually enough to allow the responses to take effect. If the temperature drops quickly, though, the roaches' defense mechanisms may not be able to react quickly enough to save the insects.
If roaches have infested and established themselves in a specific item in your garden, such as a box in a garden shed, you may be able to kill the roaches by placing the item inside a plastic bag and then placing the bag in a freezer. Leave the bag in the freezer for about five days, and then clean the item thoroughly, ensuring you dispose of all dead roaches and their egg cases, before you take the item back into the garden.