* There are no absolute reliable monitoring devices that exist today.
* Visual inspections can miss low-level bed bug populations as these can hide behind walls, outlets, baseboards, cracks in the walls, inside electronics etc. which are all locations that are out of sight for a human.  But with our bed bug detection beagles that have 200 mio olfactory cells (yes, 200 mio vs. our measly 10 mio) , they can smell minute amounts of bed bugs in those areas mentioned above, just by sniffing.
* A treatment may miss eggs that were inaccessible and these may hatch later.
* Bed bugs can go into hiding for quite some time after a meal and thus are more likely to escape the effects of pesticide treatments.  Given that they can survive on average 6 months (and in favorable environments longer than that) without a meal – long after the effectiveness of a heat treatment (one day) or a pesticide treatment (30 days), re-introduction is possible.
* There are no standardized, cookie-cutter methods for treating bed bugs.  Partly because every situation is different and every treatment approach should be tailored to it.
* Bed bugs proliferate very rapidly and thus can build resistance relatively fast to pesticides.  In fact, recent research has shown that bedbugs will develop resistance immediately after certain pesticide applications if they get a chance to feed on human shortly thereafter.  And that is VERY possible, since bed bugs DO NOT die immediately if they haven’t been sprayed directly by a pesticide.  This means that those bed bugs that escaped from a direct application of pesticide treatment will still survive for a day or two even after crossing a barrier of pesticide AND will develop resistance fairly rapidly if they get a chance to feed on human blood before the pesticide activates and gets a chance to kill them.
* One bed bug population that originated from one source can develop an entirely different resistance level  to pesticides compared to another bed bug population from another source.  The full article,  “Posttreatment Feeding Affects Mortality of Bed Bugs (Hemiptera: Cimicidae) Exposed to Insecticides,” is available here: http://jee.oxfordjournals.org/content/early/2015/10/21/jee.tov293
* Bed bugs often stop biting after an insecticide treatment.  They can sense the pesticide being applied and immediately run away from the sites of application and go into hiding places that the pesticides cannot reach, thus escaping the treatment.
* No one really understands how bed bugs behave in the absence of hosts.
* There is no way of telling whether bed bugs that suddenly reappear weeks later are newly introduced since the last treatment or are remnants of the last infestation.
I would therefore highly recommend to ask our K9s to conduct a bed bug inspection and detect those pesky elusive critters all the way down to 1 live bed bug or live egg.  Call us at 508-713-8267 or contact us here.