[Ice Chips] Answers to your toughest QA questions

Q. We have had a problem with a rat in our warehouse for several weeks. Some people see it, then it disappears for a week or so before it is spotted again. We have put out a lot of traps but cannot catch it. The rat mostly seems to be seen near the ceiling. Do you have any suggestions?

A.You may be dealing with a roof rat, not the Norway rat people commonly encounter in places away from coastal areas. According to the National Pest Management Association (NPMA), there have been a number of reports of roof rat activity at inland sections of South Carolina, Tennessee and Georgia.

Roof rats and Norway rats have a similar biology, but quite different behavior. The Norway rat mostly lives at ground level in burrows, but the roof rat tends to live in high areas like trees, roofs and ceilings. Traditional control programs that place all of the control devices at floor level and are designed mostly for mice are not effective for this rodent. You have to set up a control strategy in their territory and use the tools designed for them to be successful at elimination.

Roof areas should be monitored with bait stations equipped with an approved rodenticide or with rat size snap traps. See if you can identify runways in overhead areas by the presence of grease marks left by the rat. These are ideal locations to secure a snap trap or rat glue board placed in a piece of PVC pipe about two inches longer than the glue board. On the roof, look for areas where they may have burrowed or are using utility penetrations as access points.

It is very important to properly monitor the roof areas on food plants for rodent activity. There is data that suggests a number of rodent infestations began on the roof and the rodents found their way into the plant. AIB