Q: Something is chewing through the central ribs of my palm fronds and causing the fronds to hang midway or fall off. We have never been able to see what’s doing the damage.
I.S., Key Largo
A: From the photo you emailed me, it looks like the type of damage roof rats do. If you look closely, you can see the teeth marks. During the dry season, roof rats may be feeding on palm frond midribs as a moisture or food source since there are fewer fruits and palm seeds available then.
You can place rat traps inside a box in the crown of the palm if possible. You can also place a 18- to 24-inch-wide metal band around the trunk of the palm. Make sure that the band is not nailed to the plant since this would damage the palm. The metal band prevents small climbing animals from getting a good foothold on the trunk. If you use this technique on a broad-leaf tree such as a fruit tree, the trunk widens with age so you’ll need to check the band periodically to make sure the band is not too tight around the trunk of the tree.
You can also set traps in other parts of your landscape but you also need to get your neighbors involved since roof rats are a neighborhood problem. Avoid using rat baits and rat poisons since pets and other wildlife can be killed by either feeding on the bait or eating a poisoned rat.
You may want to hire a pest control company if you and your neighbors aren’t able to get the roof rats under control.
The roof rat is an introduced species native to southern Asia. It was brought to America on the first ships to reach the New World and has spread around the world. The secretive, nocturnal nature of rats means that they often go unnoticed in a neighborhood until dooryard citrus and other fruit starts to ripen. In citrus, papaya, and melons, the characteristic damage is a circular hole about the size of a quarter or half dollar and the whole fruit hollowed out. They will also feed on avocado and mango fruit.
Roof rats are arboreal (tree-living) by nature. They are similar to squirrels in their ability to move through trees and along vines and wires. They often use fences, utility lines, and tree branches to reach food and water and to enter buildings. They prefer nesting above the ground in attics, soffits, piles of debris, hollow trees, and in skirts of old fronds on palm trees.
To learn more about controlling roof rats, please read this UF fact sheet: http://edis.ifas.ufl.edu/uw120.