Eliminating bed bugs holed up in the deep harborage of structural crevices, and voids is problematic, which is a fancy way of saying they are just plain hard to get. Even the most powerful vacuum cannot reliably rip them from their strongholds, and they are blissfully out of the line of fire for most sprayables.

But we have more tools in the shed. Steam has proven to be very effective, but only has an effective range of a centimeter or two and it does not seem to take too many layers of insulation to protect bed bugs from the lethal effects of the steam. The use of cold, as we discussed last issue, has even more challenges in its ability to eliminate bed bugs. In the absence of the perfect and universal solution, the pest management professional (PMP) is left to consider the possible methods available for use and choose the most appropriate for each situation.

If this sounds suspiciously like integrated pest management (IPM), it ought to — multiple methods tailored to specific situations are the heart and soul of IPM. Let's consider the most common deep harborages and discuss possible solutions.

Harboring behind baseboards and inside wall voids can allow bed bugs to stay out of harm’s way. Resistant populations can survive anything, but a direct hit of pyrethroid insecticides and the heat from a steamer will not reach far enough back to give your confidence in the treatment.

Unlike cockroaches, bed bugs do not groom themselves with their mouthparts and will not ingest dusts that adhere to their bodies. This means that borate-based dusts are unlikely to have any significant effect on bed bugs. Silica-based dusts, on the other hand, act mechanically on the insect’s waxy outside coating and will work without them having to ingest the dust. You might opt for a silica-based dust to kill bed bugs deep in the void or attempting to pass through the dust.

Both silica gel dusts and diatomaceous earth are silica-based dusts. They work best in dry voids, the preferred habitat of the bed bug. While they are effective and relatively low hazard, these dusts may have label language restricting where you can apply them. As with all pesticide applications, read the label carefully.

If you intend to use heat, you will need to raise the temperature inside voids and structural crevices beyond the 113°F that has been reported as the thermal death threshold. You should aim for 120°F or 125°F to ensure the treatment is effective.

Some of the more progressive companies handling bed bugs are achieving good results using portable heaters to treat entire apartments or hotel rooms. It requires more instruction than this article can offer, and is admittedly labor-intensive, highly energy-dependent, and leaves no residual. There may be some other technologies waiting in the wings for the bed bug market, but they are not here just quite yet. In the meantime, thorough inspection and treatment will help you achieve success — even when bed bugs are hidden in hard-to-reach places.