Hard to find flies, clothes moth control & bombing for German cockroaches


February 21, 2014

Q: A residential customer has a fly problem. The county extension agent identified the flies as Sciarids and says they breed in wet organic matter. The customer had the drains and garbage disposal cleaned. We can’t find any water sources or conditions, but the flies persist. They’re mostly in the kitchen but can be found in other rooms around lights at night. What other sources can you think of? The temperatures outdoors are below freezing, so they aren’t coming from outside. J.H., Minn.

A: These flies usually aren’t associated with waste lines like Phorids, so I doubt that’s a source. One source you might have overlooked is the refrigerator drain pan. Frost-free refrigerators have a pan beneath them that collects water during the defrost cycle. Some pans are removable, and some aren’t. Remove the toe grill from the bottom front of the refrigerator. Remove the pan for cleaning. If it’s not removable, reach in and clean it best you can. I’d also put plastic wrap or plastic cups over all drains to see if any flies collect there. If so, the drains need to be cleaned again.

Q: When we get a clothes moth job, we advise the client to have all woolens dry cleaned. One client recently told us you could put the affected clothing into the freezer for four hours. We said OK but extend the period to 72 hours. What about cold for clothes moth control? J.T., Colo.

A: Cold isn’t always an effective control method for some insects. Even freezing might not give you 100-percent kill. Remember, most insects survive winter outdoors. Long-term (months) freezing might provide control, and temperatures below 40 F will prevent growth and reproduction, but you don’t always get kill. Heat is a much better control tool. As a general rule, 30 minutes at 115 F will kill all stages of almost every insect. For clothing, a stint in the dryer will probably do the job. Dry cleaning is still a preferred method, especially for large items such as wool suits and coats.

Q: What’s your opinion about fog bombing a restaurant for German cockroach control? I understand cockroach mortality would be minimal because cockroaches can close down their respiration and metabolize the active ingredients. J.B., S.D.

A: Cockroaches can metabolize natural pyrethrins well. You can knock them down, but most get up and live another day. Such space treatments also tend to scatter the populations, and many cockroaches simply move into new harborages. The advantage of space treatments using natural pyrethrins is that cockroaches are flushed from their harborages, which allows you to identify harborages you might have missed during an inspection. Additionally, if you use a residual first, the cockroaches are driven onto it, which provides a high degree of kill. Another option is a sound bait program plus an insect growth regulator. pmp

You can reach Dr. Mampe, an industry consultant, at dentomol@aol.com

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