There are a number of factors that influence how long it takes to get rid of bed bugs. The factors include how long the bugs have been present, the cooperation level of the host, the client’s self treatment attempts, the amount of clutter present, the type and placement of the sleeping furniture, the pesticide resistance level of the bugs and the physical environment.
Though there are exceptions, when the infestation levels are very small, all the bugs are on the sleeping surface. There have been a number of occasions where we heated the sleeping furniture, applied zero pesticides, put glue board monitors under the bed legs and found no further activity. In these cases it took exactly 1 day to get rid of the bugs. Sometimes in these small infestations we might catch a handful of bugs on the glue boards over the course of a week or two and that removed all the bugs. As the infestation levels increased the amount of time increased proportionally.
In the most severe infestation I have addressed the bugs leaked out of the walls for 6 months. The infestation was so severe that there were bugs behind the stove in the kitchen which is very unusual. We removed all the baseboards and door frames (which sometimes had a quarter of an inch of harbourage material) and sprayed all those areas with a residual insecticide. All furniture was also carefully treated with insecticide (the chemical application was repeated two weeks later as well). The landlord also assisted the tenant by taking all cloth items in the suite to the laundromat. The beds, baseboards, and frames were heat sterilized in my heating trailer. The beds were then returned and isolated with glue board traps under the bed legs. We then proceeded, despite the chemical treatments, to catch over 500 bugs in the glue board traps every single night for at least 2 weeks!! As time went on the number of bugs caught decreased. Toward the end of the 6 months perhaps only 1 bug would be caught in a week. It has now been two years and that suite is still bug free.
When clients cooperate with the exterminator the amount of time it takes to get rid of the bugs is also reduced. For example if the client faithfully puts on clothes fresh from the dryer before leaving the home the likelihood of reinfestation from external sources decreases. If the tenant has friends with bed bugs who visit regularly the home will never be reliably free of bed bugs. In my own experience it seems that a bug free suite is infested on a yearly basis (or perhaps even more often) when friends with bugs visit regularly. Or if the tenant visits people with bed bugs (or has already infested the workplace) the same problem occurs.
If the client has been using non residual pyrethroid chemicals (RAID, KONK, etc) the bugs tend to harbour in areas further away from the bed. This fact, in turn, extends the amount of time required to get rid of the bugs.
If a home is incredibly cluttered the likelihood of successfully removing the bugs are close to zero. For example I was asked to address a bed bug problem in a private home that had every wall filled with books, magazines, and other items. A whole house heat treatment was previously attempted and the client reported a 1 week reprieve from the bugs. A chemical application would be equally ineffective because very little of the home was actually accessible for treatment. Also during regular chemical treatments the bugs tend to abandon areas that have been treated. If the bugs have any amount of resistance they will alternately harbour in areas not treated by chemicals. If there is a lot of untreatable clutter the bugs will simply migrate to those areas.
The furniture type and placement is also important. If a tenant has a mattress on the floor the bugs tend to push out from the bed and infest surrounding furniture and baseboards. The further the bugs are pushed from the sleeping surfaces the more difficult it is to get rid of the bugs. The same is true for a bed with encasements. The bugs push elsewhere. Or perhaps a large stuffed couch is the sleeping surface in which case it is virtually impossible to get the bugs out if it because there are huge areas that are inaccessible to chemical or steam treatment. If the tenant insists on keeping the couch it may be impossible to get rid of the bugs.
The level of pesticide resistance is key in the length of time it takes to get rid of the bugs. In some cases we are able to treat an unprepared suite with minimum cooperation from the client and we were successful with the first application. Wow! In other cases I have chemically treated a large harbourage on the underside of a couch and found first instars walking around on the treated area 9 days later! This suite was very difficult to treat and i resorted to heating all furniture and isolating the furniture with glueboards which did eventually get rid of the bugs. Most of the cases an exterminator addresses are somewhere between the two extremes of easy to kill and virtually impossible to kill with insecticides.
And finally the physical environment is key as well. If you live in multi family housing where no one cooperates you will never get rid of bed bugs. It is in these cases where the management simply treats on a monthly basis to fulfill legal obligations with no hope of ever actually killing the bugs. If you live in a home where the variables are much more controlled the likelihood of success is much better.
As we can see how long it takes to get rid of bed bugs is very difficult to answer. If you have a small infestation with excellent client cooperation the prognosis is excellent. If you have a large infestation, constantly visit other infested areas, have resistant bugs, can not cooperate, insist of self treatment efforts, and live in a building with like minded folks the prognosis is very poor. How long it takes to get rid of the bugs depends on a host of factors.