When Treatments Don't Work

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If the goal is to eliminate bed bugs, the job has to be done correctly. Bed bugs are so small that they can live in a crack the width of a credit card, increasing the control challenge.

Pesticides often are an important part of a control strategy but they must be used properly for the treatment to work. There can be many reasons for failure of a pesticide treatment to completely control the bed bugs, including:

• Not finding all the bed bugs.
• Inadequately preparing area (failure to remove clutter, seal cracks and crevices, etc.).
• Overlooking treatment of any of the known resting areas (bed bugs may rest or hide in hampers, bed frames, even furniture).
• Failing to treat nearby areas where bed bugs may have migrated (adjacent rooms or other apartments in multi-dwelling housing).
• Disregarding recommended label rates (applying pesticides at too low a rate may not kill bugs and may speed up development of resistance to that chemical).
• Not following up on treatment in an appropriate timeframe (many pesticides will not kill eggs, so treatment must be repeated after the eggs hatch, or the infestation will not be controlled).
• Not allowing enough time for a pesticide to work (some pesticides, such as drying agents or growth regulators, may be effective but take some time to kill the population).
• Bed bugs becoming resistant to a specific type of pesticide.
  • As insects, such as bed bugs, are exposed to a pesticide over time, the most susceptible ones are killed first, leaving only the less susceptible ones to breed. This can result in a rapid decline in relative effectiveness of the pesticide.

Pesticide Resistance as a Cause of Treatment Failure

While there is evidence of resistance in some populations to certain types of pesticides, pesticide resistance can only be verified in laboratory tests. Researchers are currently trying to determine the scope of the resistance problem, which will vary from community to community. This research will support the development and use of effective control strategies.

Because of the potential for resistance, homeowners and others trying to control bed bug infestations must always use pesticides appropriately and according to the label. It is also important to:

• be vigilant in surveillance, identification, and monitoring efforts;
• hire trained, experienced, and reputable pest management professionals; and
• use a comprehensive approach.

For example, you may wish to:

• choose different types of pesticides from the list of currently labeled ones for sequential treatments; or
• use pesticides for which insect resistance has not yet been reported, such as diatomaceous earth, in combination with other control techniques.

Remember, as illustrated in the list above, resistance is only one of many possible causes of a treatment failure. All possibilities must be explored in any situation.