How Fast Can Infestations Grow?

Editor’s Note: This article was reprinted with permission from Pinto & Associates.

There are many factors that affect how long a bed bug lives and, consequently, how often it reproduces. As with any other creature, the length of its life and reproductive potential depends on genetics, the quality of its food and how often it is able to feed, temperature and other environmental conditions, and avoidance of physical injury. A bed bug living in controlled and favorable conditions in an entomology laboratory may have a very different lifespan than the average bed bug in one of your accounts. The pampered lab bed bug can be expected to live six months to one year, while the average bug in multi-unit housing, for example, can expect a much shorter life.

In the real world, bed bugs living around a resident’s bed face the following hazards: competition from other bugs for food and harborage, exposure to pesticides and other chemicals, crush risk from their hosts during feeding, predators such as spiders or ants, and more. Adult female bed bugs face an additional risk from traumatic insemination. During mating, the male actually punctures her body wall to inject sperm, a process that can cause injury and even death. Even so, we know that each female potentially lays eggs (150 to 500 viable eggs during her lifetime), and bed bug populations can grow quickly when real-world hazards are limited.

Because it’s hard to find and track bed bugs in the real world, we rely on lab studies where we can observe them. One group of researchers (see Polanco reference in the box below) studied the potential population growth of field-collected bed bugs that were highly resistant to pyrethroid insecticides. They found that the resistant bugs went from egg to adult in just 35 days, and populations doubled in size every 13 days.

Another study (see the Periera reference) used simulation models to predict population growth. Under restricted conditions and beginning with a single male and female bed bug, the population grew to 300 bed bugs within 15 weeks. As would be expected, when the bugs were given more food, the population increase was greater.

These are theoretical calculations based on controlled lab conditions and do not necessarily reflect what happens in bed bug accounts. We know that low-level populations of bed bugs in infested apartments sometimes fail to increase and may even decline without any control measures being taken, indicating that bed bugs face many pressures still unknown to us.

The authors are well-known industry consultants and co-owners of Pinto & Associates.