Bathroom Roaches

Saturday September 15, 2012


Mr Pest Control


In a bathroom on the second floor of my home there is one solid window above the bath which lets in light but does not open. It has an extraction vent and an air condition vent. In the past couple of days I have seen roach nymphs in there, always high on the walls or on the ceiling. Yesterday I used DeltaDust in and around the pipe openings of the toilet and under the sink, dusted around/behind the mirror, and treated crevices of the kick board at the base of the cupboards that the sink is on. I dusted around the small window. I walked into there tonight with my daughter and there was another active one walking around on the ceiling. What am I doing wrong here? Obviously an Ootheca has been dropped somewhere. Could they be coming through either one of the vents around the window?

Steve, FL

Mr Pest Control


A couple of things are a little out of character here. It sounds like you may be seeing these roaches during the daytime, in some instances, and of course this would be unusual for German roaches. You don't indicate that you have determined the actual species of these roaches, so I am assuming (perhaps incorrectly) that they are Germans. In fact, are you absolutely certain that these are cockroaches? Since they are in the nymph stage is there a chance that you may be encountering some other similar insects, even immature stink bugs or some other "true" bug? The ID could be important as there are some kinds of roaches, including the Asian cockroach in Florida where you are or in the west perhaps the Vaga roach, that are drawn to lights. Just in case the window is where they are gathering perhaps it is the bright area that is drawing them, and if so then they would be just accidental visitors to the interior and the source would be outside. 

A second out-of-character issue is that very early instar German roaches tend to stay in hiding, feeding on fecal pellets of other roaches or dead insects they find there. To be finding them out and about on different occasions is curious, but I am at a loss to explain why, particularly if you had not treated the potential harborage sites previously. As we know, German roaches most often enter structures with infested materials and packaging, and many other roaches enter from the outside where they may live in foliage or beneath things on the soil. The Asian roach adult is drawn to lights and since it can fly it could make its way to that second floor window, but this does not seem likely if it is only nymphs. I suppose a gravid female may have entered and dropped the egg capsule inside, but once again the gravid females also tend to remain inactive and in hiding while they are carrying the egg capsule. 

So, I'm not of much help here. It could be useful to get an ID to species, which can be tough when dealing only with nymphs. You might try sealing off those vents around the window temporarily to see if this presence inside stops, and maybe even use some glue traps right there to see what is caught by the vents. 

Mr. Pest Control

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