Ask the Expert: Chipmunks, Mice, Bed Bugs and Cockroaches


February 10, 2015

Q. I’m baiting for mice on the exterior of a residence at the request of the homeowner. Recently, chipmunks have been feeding on the blocks in the stations and dragging them out when the blocks fall off the wire rods. We’re concerned about the bait exposure. Is there any way to keep the chipmunks out and still bait for mice? Frank I., Vermont

A. If you keep the chipmunks out, you’ll also keep out the mice. Consider water baits in the stations. Mice will drink water if it’s readily available. Another option is to replace the blocks with pellets. The chipmunks will take the pellets out of the stations, but will seldom leave any exposed. Expect to lose a lot of bait, however.

Q. Another pest management company in my area is touting DNA samples to determine whether bed bugs are present in a building. Can they do this using DNA samples? How long does DNA last on a surface? How accurate is such a test? John B., Alabama

A. DNA samples can determine whether bed bugs have been present on the sample swabbed. However, DNA is very stable. If the sample is positive, it doesn’t indicate whether there’s an active infestation. It only tells you bed bugs were present at some time. Bed bugs might have been present two years earlier. It seems like a marketing gimmick to me. If the company sells a treatment for every positive sample, it will sell a lot of bed bug jobs.

Q. I service a school that has a kitchen in the basement and another kitchen directly above it. Every year, beginning around April, Oriental cockroaches (Blatta orientalis) come out from the floor drains in both kitchens. The activity stops around early October. This fall, they opened the septic tank to clean it, and the cockroaches crawled out by the hundreds. Is the septic system the source? Could I put screens over the floor drains to prevent the cockroaches from entering? Can I treat the septic system? If so, how and with what? Why don’t I see the cockroaches during the winter months? Fred E., Pennsylvania

A. The septic system is probably the source of the problem. You don’t see cockroaches during the winter because it becomes too cold in the septic system, and activity ceases. Placing screens in the floor drains would likely stop the cockroaches, but because food particles could clog the screens quickly, that’s not a viable plan. The septic system is probably open, so bait inside as heavily as you can. This might mean gel baits on the underside of the cover, but you might find other spots to bait. Put an insect growth regulator (IGR) into the system to slow down breeding. IGRs can be volatile, so treat any surface you can, and the IGR will migrate to other areas of the system. Begin treatments as soon as possible, and follow up every three months. You might need to bait more frequently, if that’s practical. The IGR will give you as long as three months of protection.

Email your questions about insect identification and pest management technologies and techniques to Dr. Mampe, an industry consultant, 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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