Ask the Expert: Tackling Fruit Flies in Pools, Freezing Bees & More


June 12, 2014

Doug MampeQ: A customer has a screened-in lanai and pool but fruit flies find their way in, almost daily. We’ve inspected everything possible without finding a source. There are numerous fruit flies in the lanai, and some were found outside. Can they get through screening? Is there a screen size that should be used to prevent this? G.C., Fla.

A: Screens come in opening sizes measured by the number of threads in an inch. Standard screens are usually 14-by-18 threads-per-inch. So-called insect-proof screens are 20-by-20 threads per inch. If the problem is coming from outside the screening, you need finer screening, which is more expensive.


Q: I do many bee jobs every year. I like to harvest the honey, but if a pesticide dust or spray is introduced within the hive wall, the honey will be contaminated. I’m thinking about using Cryonite to freeze the bees and harvest the honey. Would this work? If not, do you have any suggestions? J.B., Ind.

A: It’s an interesting idea, but I have reservations. To kill insects with Cryonite you must make direct contact with them. If you’re treating a honeybee colony in a wall void, I doubt you can reach all the bees directly. When you open up the wall, you’ll have live bees flying into the home, which can create a bigger problem. Repeated applications might solve the problem, but time becomes a factor. I doubt treating with Cryonite (or a similar process) can kill almost all the bees in a wall void filled with insulation and honeycomb. Your best alternative is to become a beekeeper, trap the colony, relocate it and harvest the honey. If you have easy access to the colony, Cryonite might be effective, but in most cases, I doubt you can achieve the level of control you desire.


Photo: ©

Bleach won’t solve a drain fly problem because it doesn’t penetrate the organic goo that builds up in a drain. (Photo: ©

Q: I service a hospital with a drain-fly problem. The hospital maintenance staff is pouring bleach into the drains almost every night, but the infestation persists. I want them to use a microbial or enzyme product and switch to a product I use for drains. I need reasons for them to stop using bleach. How would you approach this? R.K., Okla.

A: Bleach won’t solve the problem. It doesn’t penetrate the organic goo in the drains, so the problem continues. Bleach also produces vapors I wouldn’t think the hospital would want. Furthermore, if the drains are cast iron, bleach will slowly corrode them. Almost all of the enzymes or biological products available to us works — some better than others, but all of them beat bleach. Why not sell them a maintenance program so you can treat the drains? You don’t need to do it every night. Treating once every week or two will work. pmp


You can reach Dr. Mampe, an industry consultant, at


Email your questions about insect identification and pest management technologies and techniques to Dr. Mampe at Your questions most likely will be printed and answered in one of Pest Management Professional’s upcoming Ask the Expert columns.

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