Jan 12, 2012 – Lingering Roaches
QUESTION:
A customer has German roaches, primarily in their kitchen by a dishwasher area. The house is REALLY nice and they are very clean in terms of food waste. I am surprised the roaches have somehow been there for months or longer to some degree. On my initial visit I focused more on gel bait application in the kitchen - cabinets, around dishwasher, under sink, drawer tracks, behind stove, etc. After 2 weeks they said they have noticed a decrease, but still have some. On this visit I focused mainly on non-bait approaches, including CB-123 flushing agent mostly around the dishwasher, which is between a sink and an end cabinet. Those 3 areas have been the most active areas. There's a hot water heater under the sink, and that along with the dishwasher, and maybe the fridge motor are, in my opinion, likely warm spots roaches might be seeking. It appears to be at a place where they have a low-med degree of live roaches, dead ones found as well, but I don't know what to do. Do you think more bait and less flushing would be a more effective approach? Does CB-123 aerosol provide a residual that is good for longer than a few hours or days? Does it repel activity from the areas it was sprayed for that time length, or is it likely for those treated areas to be considered clear and vacant harborage to potential other insects a few days after they were treated? I used DeltaDust in some areas, one of them being a square metal electrical box that seemed like it would be a likely roach hiding place. I sprayed the baseboard areas in the kitchen with Masterline Bifenthrin 7.9 mixed about as high as legally allowed, and hope it works well with the flushing agent and dust. Would more gel bait would be a wise choice if they still have roaches, or do you think it would not really be effective now that above chemicals have been applied? Do you think in a week or two, the residual poisons will have affected a good portion of the current roaches?
ANSWER:
You had a pretty long question Christopher, so I did abbreviate some of it but hopefully did not detract from the overall meaning. You also ask quite a few questions, so let's see how well I can organize my responses to them. First on CB-123, which is pyrethrum. This is a very non-residual active ingredient that should be used primarily for flushing of German roaches, and by "flushing" we really mean it is best used as an inspection tool, not a control product. Pyrethrum is highly irritating to roaches and will drive them out of hiding quickly, showing you where you have pockets of roaches so that you do not miss treating those harborages. Pyrethrum by itself, even synergized as it is, will kill some roaches but would not be expected to kill them all, so even the ones driven out could recover. Even though the pyrethrum residual, from all I have gathered over the years, is no more than a few hours it could leave some repellency in the voids and crevices you treat. This is not necessarily a good thing, for roaches are going to find somewhere else to hide that may be more difficult for you to find and treat. Best to use pyrethrum sparingly as an inspection tool only for roach control.
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A customer has German roaches, primarily in their kitchen by a dishwasher area. The house is REALLY nice and they are very clean in terms of food waste. I am surprised the roaches have somehow been there for months or longer to some degree. On my initial visit I focused more on gel bait application in the kitchen - cabinets, around dishwasher, under sink, drawer tracks, behind stove, etc. After 2 weeks they said they have noticed a decrease, but still have some. On this visit I focused mainly on non-bait approaches, including CB-123 flushing agent mostly around the dishwasher, which is between a sink and an end cabinet. Those 3 areas have been the most active areas. There's a hot water heater under the sink, and that along with the dishwasher, and maybe the fridge motor are, in my opinion, likely warm spots roaches might be seeking. It appears to be at a place where they have a low-med degree of live roaches, dead ones found as well, but I don't know what to do. Do you think more bait and less flushing would be a more effective approach? Does CB-123 aerosol provide a residual that is good for longer than a few hours or days? Does it repel activity from the areas it was sprayed for that time length, or is it likely for those treated areas to be considered clear and vacant harborage to potential other insects a few days after they were treated? I used DeltaDust in some areas, one of them being a square metal electrical box that seemed like it would be a likely roach hiding place. I sprayed the baseboard areas in the kitchen with Masterline Bifenthrin 7.9 mixed about as high as legally allowed, and hope it works well with the flushing agent and dust. Would more gel bait would be a wise choice if they still have roaches, or do you think it would not really be effective now that above chemicals have been applied? Do you think in a week or two, the residual poisons will have affected a good portion of the current roaches?
ANSWER:
You had a pretty long question Christopher, so I did abbreviate some of it but hopefully did not detract from the overall meaning. You also ask quite a few questions, so let's see how well I can organize my responses to them. First on CB-123, which is pyrethrum. This is a very non-residual active ingredient that should be used primarily for flushing of German roaches, and by "flushing" we really mean it is best used as an inspection tool, not a control product. Pyrethrum is highly irritating to roaches and will drive them out of hiding quickly, showing you where you have pockets of roaches so that you do not miss treating those harborages. Pyrethrum by itself, even synergized as it is, will kill some roaches but would not be expected to kill them all, so even the ones driven out could recover. Even though the pyrethrum residual, from all I have gathered over the years, is no more than a few hours it could leave some repellency in the voids and crevices you treat. This is not necessarily a good thing, for roaches are going to find somewhere else to hide that may be more difficult for you to find and treat. Best to use pyrethrum sparingly as an inspection tool only for roach control.
Second on the bifenthrin that you sprayed around baseboards. A much better use of residual insecticides for roach control is to apply it directly INTO cracks, crevices, and voids where you suspect the roaches are hiding. This offers several benefits. First, the material is then not exposed to light or washing that could minimize its residual. Second, it removes the material from contact by people or pets. Third, it places the active ingredient into the places where the roaches will spend 80% of their time, dramatically increasing the length of time the roach is exposed to that a.i. and is absorbing it into its system. The key to success with insecticides is to put the pest and the active ingredient into contact with each other for as long as possible. Applying the material to open surfaces where the roach may do no more than run across the treated surface might not provide that sufficient contact time. The roach in long contact with a residual like bifenthrin should begin feeling the effect within hours, so if they have absorbed enough to be lethal to them they certainly should be dead within 24 hours.
Dusts are excellent products for roach control when used within voids that will not be opened by people, potentially exposing the people to the visible dust that they know is "roach poison" and which now worries them regarding their exposure and health. Wall voids, hollow voids of equipment such as side panels of stoves or dishwashers, beneath this permanent equipment, etc. An inorganic dust like silica gel or DE will kill the roaches more slowly, but dead is dead, and these dusts last forever and offer little human health concerns. DeltaDust is excellent too, but it is going to degrade and become ineffective after months to maybe a year.
Baiting is also excellent, and probably should always be part of a German roach control effort. The baits available today are so acceptable to these roaches that keeping them available where roaches are still active is a good idea. Contrast the bait arsenal of today with that of 30 years ago, when there was a single bait - Baygon Granules - and you recognize the benefit of what we now have. I would suggest using a variety of bait products just to keep the roaches interested and replacing the bait after a few weeks to maybe a couple of months to ensure it is still fresh and palatable. Some baits seem to last longer than others, which may dry out and become harder and less tasty to the roach. Be sure to place gel baits directly into crevices, not out in the open. According to our experts the German roach prefers to feed in seclusion, and a pea-sized blob of gel bait found in a crevice affords the most acceptable food for it. Do not bait in long lines of material - just individual blobs.
Since this sounds like a private home, not an apartment or some other multi-family structure, eradicating the roaches should be possible and the goal. You would not have the influence of roaches migrating in from neighboring units. Perhaps the reason for this lingering presence is new roaches emerging from dropped egg capsules. Perhaps it is from some missed harborages that have roaches that are not yet exposed to anything. Be certain it is German roaches and not Brown banded roaches, for the BBR may be hiding anywhere within the home. Sometimes it is of value to take the flashlight and do another complete "initial" inspection to see what may have been missed. Immunity to these insecticides really is not an issue, so if the roaches are eating the bait and in contact with your residual materials they WILL die.
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