The question you have asked is the bases for a good PMP article. Swarms After Treatments. Best I know there is little scientific data to prove this happens as a result of the treatment or not. In the field we have all experienced swarm within six week of new applications, and for whatever treason these are the first to swarm in the next swarm period either fall or early spring/summer depending on where you are located in relationship to the equator.

              Old information’s lives forever weather right or wrong. Backing up to chlordane and heptachlor (hep·ta·chlor), the emulsifier in both products was xylene, this created vapor pressure, so when using either product singly or when they were combined like Orkil  (Chlorhepton) or Termide you could get a flushing action from the heptachlor that has a vapor pressure of 10 which is much higher than chlordane.

          Vapor from Dursban also had a vapor pressure that caused a flushing action after application. When Dow switched to water base and change the dilution this problem stopped.

          All of the first generation pyrethroids also used xylene as their main emulsifier and they even created more vapor resulting after treatment swarms.

          When termites swarm in structures in the same place as last year or swarm season. That generally mean for whatever reason that group (colony) was missed last year and the exception can be they found a moisture supply above ground, examples shower stall, wax ring, leaking, tub or shower, chimney, roof, pipe protruding through the sealing, clogged gutters or down spouts, ice dam, and just plain roof leaks at nail backup’s.

          What do you think?