Identification is at the heart of a solid integrated pest management (IPM) plan, and while we tend to take the time to identify insects, that step often gets overlooked when it comes to rodents. Once we discover rodents — or evidence of rodents — we may go into auto-pilot and throw down some traps, inspect the area, change the bait and hope for the best.
But the three main commensal rodents — Norway rat, roof rat and house mouse — have important differences in their behavior and preferences that we must consider in our monitoring and control strategies for them to be successful.
The roof rat (Rattus rattus) is a common pest in the southern half of the United States, but every year we see them creep farther north. PMPs that execute a rodent management plan that was successful for Norway rats (R. norvegicus) will find that same plan simply won’t work for roof rats.
With Norway rats, we tend to focus on the ground for burrows and travel paths, while roof rats are found up high. That means we need to work at a higher level — literally. Traps placed on the ground may not be effective, so instead we must explore ways of deploying them in ceilings, zip-tying to racks, placing in attic voids, etc.
Likewise, a Norway rat typically has different needs than a house mouse (Mus musculus). Rats need free water and will seek it out, whereas mice tend to have all of their water needs met from the moisture in their foods. This may play an important part in our choice of lure (cucumbers and tomatoes often are very attractive to rats) and where we inspect for activity or harborage.
Before you commit to a control strategy, make sure you know exactly who you’re dealing with so you don’t waste time targeting a pest that isn’t there.