Pest Management Professional, April 2012

Dr Doug Mampe Contributor Q I just encountered a new construction feature that has developed a fungus gnat problem Its a flat roof covered with soil that has ornamental grasses planted on it Im told that beneath the soil is a bathtub that retains rain water to prevent run off There is a provision for drainage if the water level becomes too high in the tub Directly below this construction feature is a large conference room Fungus gnats are being found there The room has floor to ceiling windows which attract the gnats No moisture source can be found I was told the tub leaked at one time but has been repaired The ceiling is 20 feet high and covered with wood slats I cant reach the underside of the roof to take moisture readings What would you do RH N Y A The roofs construction likely caused the fungus gnat problem When the earlier leak was repaired all wet materials should have been removed A common mistake is to just repair the leak Once the ceiling is closed there is little air circulation in the roof structure drying will take years to occur if it occurs at all If you can get the blueprints of the roof construction you might be able to deduce where the source is In the meantime I suggest treating the window sills with a pyrethroid residual The gnats will contact the pesticide and die more quickly than they will if no treatment is made I doubt light traps will be effective in this case because of all of the light competition with the windows Also light traps probably would not be aesthetically acceptable here Eventually the problem will become worse and an engineer will be needed to locate and repair the leak The design also might be producing normal condensation I would discuss these issues and other variables with the owner sooner than later Q I have treated several apartments for bed bugs The owner has left the units vacant and turned the heat down to 50 º F The owner wants assurance the bed bugs are gone Are bed bugs active at these low temperatures How do I determine if the infestation has been eliminated Will a bed bug scent detecting dog help J B Minn A This problem is much like a flea infestation that appears to be solved until the apartment is reoccupied Fleas typically dont emerge from their pupal cases unless there is movement vibrations in the room As soon as someone occupies the apartment more flea adults emerge To get bed bugs to move you need to get the room temperature up to 72 º F or higher Then install one of the active bed bug monitors which contain heat CO 2 and or attractants to determine if the pests are present A properly trained bed bug dog also could be used to detect the presence of live bed bugs If bed bugs are found keep the space at room temperature 72 º F or higher to encourage the pests to cross your residual treatment PMP You can reach Dr Mampe an industry consultant at dentomol@ aol com ask the expert To get bed bugs to move you need to get the room temperature up to 72 º F or higher Please email any questions you have about insect identi cation and e ective pest management technologies and techniques to Dr Mampe at dentomol@ aol com Your questions most likely will be answered in one of PMPs upcoming Ask the Expert columns mypmp net Pest Management Professional April 2012 63