Common Palm Insect pests in north and central Florida
- palmetto weevil
The palmetto weevil can kill a large Canary Island date palm very quickly.
Palmetto weevil damage quickly becomes evident as the upper fronds of the attacked palm collapse often giving the impression that the top has fallen out of the palm tree. The lower fronds can remain green for months. But without the palm bud, the palm tree dies.
The primary target of the palmetto weevil, an insect native to Florida, is the Canary Island date palm. Date palms, sabal palms and Washingtonian palms are also susceptible to attack by the palmetto weevil.
The palmetto weevil adults are large, about one inch long. (Photo by Dr. Doug Caldwell, University of Florida, Collier County Extension Service, Naples, FL)
Generally, stressed palm trees are attacked which means recent palm transplants undergoing transplant stress are prime targets for the palmetto weevil. The adult weevils (photo right), sensing the stressed palm, congregate at the base of the fronds to mate. The female weevil then deposits eggs at the base of the fronds. When the eggs hatch, the grubs that hatch chew into the center of the palm where they attack the bud, the crucial growing point of the palm. The grubs are eating palm heart like the palm hearts available in cans at the supermarket. Except in this case they are eating your palm heart.
The immature grub stage is the culprit that kills the palm. The grub is large, about the size of your thumb, and can do extensive damage to the palm heart or bud. Often there are many grubs infesting the bud assuring a quick death for the affected palm. Then slowly the top starts to bend over and some of the fronds collapse. If diagnosed early in the collapse of the upper fronds, we can sometimes find some grubs still at work. It makes quite an impression when one of these huge grubs is plucked out of the crown and dropped at the feet of the homeowner.
The palmetto weevil pupal stage is large, about the size of your thumb. Even if the grub cannot be found, its large tunnels can be found at the base of fronds that have collapsed.
(Photo from University of Florida files)
When the grubs have already feasted, pupated and then turned into adults searching for a mate and another susceptible palm tree, evidence of their work can always be found. Such evidence is in the form of tunnels the diameter of your thumb in the base of some of the collapsing fronds or frass pellets (photo below).
View of the frass pellets left near the tunnels made by the palmetto weevil grubs.
(Photo from University of Florida files)
Once the palmetto weevil damage becomes visible, there is no hope of recovery even with a subsequent treatment of a strong insecticide drenched into the crown. The damage has been done.
I do not normally like to recommend preventative treatments for most insect problems in the landscape. However, a preventative treatment can be appropriate for a high value palm. Prophylactic treatments of an appropriate insecticidal crown drench are recommended twice a year for high value palms such as Canary Island date palms. Unfortunately, these preventative treatments are only partially effective in preventing an infestation. Contact your local Cooperative Extension Service office (usually found under a county government listing) for a pesticide recommendation for such a preventative treatment.
The infested sabal palm folds over on itself after the palmetto weevils consume the bud. This was a recent transplant and the stressed palm attracted the weevils.
(Photo by Chuck Lippi)
