Adult bed bugs can live for up to a year without feeding. This ‘fact’ is quoted pretty often around the internet and even Rentokil’s own pages quote it. Even the National Health Service has signed up to it.
There is an important caveat with this fact: the temperature. Adult bed bugs (Cimex lectularius) are only capable of surviving for over a year at 10 degrees centigrade. The fact has been debunked by worthier authors than myself, including the excellent Insects in the City blog: -the actual situation is that adult bed bugs kept at 26°C will probably not survive longer than 100 days following their last blood meal. Another important observation from a recent academic investigation into bed bug longevity is that some breeding lines of bed bugs resistant to some modern insecticides have shorter life spans after their last meal. Rather than rehash that work let’s look at why cooler temperatures lengthen the life span of a bed bug.
Insects are cold-blooded and are a great deal more active when environmental temperatures are higher as they need a body temperature above a certain threshold in order to move and undertake other high-energy activities. Warm-blooded animals have internal mechanisms to maintain their body temperature within a certain range to able activity and a wider range of temperatures. The process of maintaining a stable body temperature itself requires a lot of energy and so warm-blooded animals tend to eat a lot more than cold-blooded animals.
Below a certain temperature cold-blooded animals such as bed bugs go into a ‘chill coma’ where they are inactive, but not dead. They wait until the conditions warm up so they have enough energy to be active again. Whilst they are waiting their metabolism is is very slow indeed so they need not use much energy in maintaining vital processes. The temperature required to kill an insect (the ‘cold death’ point) is much, much lower than the temperature required to induce ‘chill coma’.
A bed bug never knows when it will get its next meal and being cold-blooded suits it rather well. Humans like sleeping in warm places and that warms up the bed bugs and they become active and feed. An inability to regulate body temperature can also work against bed bugs in that they are susceptible to death when their environment warms up far much. Recent work investigating the point at which bed bugs die when heated shows that 47°C should be sufficient to kill adult bed bugs.
Rentokil make good use of this limitation in bed bug physiology with our Entotherm heat treatment process. At that temperature, enzymes that regulate cellular processes in the insects state to denature and the cell membranes themselves start to change structure leading to a rapid death.
The bottom line is that bed bugs can’t really survive without food for a year, unless it’s really chilly in your house (it makes a change to read something that makes bed bugs a bit less scary for a change).