A few decades ago, the issue of bed bug infestation was not a major problem. Most of the insecticides and washing detergents then could easily kill them, and this resulted in their diminishing numbers. In the recent past, however, there has been an increase in the number of bed bugs in western countries, and this could be tied to the approach that people have towards the use of some forms of insecticides.
For instance, the use of DDT was abundant a few decades ago. This insecticide was very effective against most insects including bed bugs, and was widely used to control them. However, after further research, it was shown that this compound did more harm than good, and its use was severely limited. In addition to that, the components of insecticides also had to conform to stringent laws to ensure that they were relatively safe for the environment as well as for people and pests who might come into contact with them.
As a result, bed bugs have begun to proliferate at an unprecedented rate, since there are very few chemicals that can be used to keep them in check. Regular insecticides are not effective, since the bed bugs have developed resistance to some of the chemicals within the insecticides.
A few of the insecticides that might be effective against them including malathion are not meant for use indoors, which further exacerbates the problem. Newer current insecticides such as EcoRaider® are proving to be effective, and increased use could result in a decrease in bed bug numbers. Due to these factors and more, bed bug numbers are being seen to rise, and may continue to do so in the foreseeable future.