Over the years I have noted that aerosol pyrethrins cause tremendous damage by scattering bed bugs over a wide area. Scattered bugs are more prone to be transported to cars, work places, friend’s house, neighboring suites, etc.
A few weeks ago I started a new multi family account and one of the first jobs I had to do was address cockroaches that had been unsuccessfully treated for over one year. I understood from the tenant that the exterminator had applied 2 courses of maxforce gel (pcp 24240) which was good. On the other hand I noted that only the kitchen had been treated which is not optimal. After that attempt failed several courses of “spray” had been attempted which also failed. As I began treating I noted the roaches were thinly scattered over the entire home. All four bedrooms, and the living room had live activity.
Normally cockroaches are centered in the kitchen and bathroom and occasionally we find them elsewhere which made this presentation very odd – the bugs were evenly distributed throughout the home. I inquired about the tenants self treatment efforts and was informed that he had been encouraged to self treat with aerosol pyrethrins. Now I have only treated about 100 cases of roaches so my experience is limited but I found it interesting that aerosol pyrethrins seemed to have the same scattering effect on cockroaches as it does on bed bugs. It may also be the case the aerosols contaminated the gel baits which caused the bugs to avoid the gel which caused even more harm.
If I find more cases like this I will update this blog to reflect additional experience. Till then I will be discouraging self treatment efforts for cockroaches.
Update August 15, 2015
I was asked to assess a private home that had a 3 year old infestation of bed bugs and also a very large infestation of cockroaches. The home had never been professionally treated for either insect but rather was treated periodically with aerosol pyrethrin (RAID). The bed bugs showed classic dispersal patterns with bugs harbouring in plain view on the ceiling. Interestingly the cockroaches were equally dispersed with large numbers of them observed in every room of the home including the basement. At one point I noted a cockroach sitting about 3 inches away from a mans head as he sat on the couch (should I say something? Bit awkward). I personally watched where I stepped as the immatures were constantly scrambling about the floor.
The main difference between the two cases was that the first one had been professionally treated and the numbers were much fewer than the second where only aerosol pyrethrin had been used. But the constant between both settings was the widely dispersed nature of the infestations. Don’t self treat!