Oak Tree Caterpillars and Leaf Rolling Weevils Taking Over Tampa Bay

Oak Tree Caterpillars and Leaf Rolling Weevils are taking over Tampa Bay, by Mark Govan, Host of “Florida Gardening” on 970WFLA Sunday’s 7-9am.

I do not mind when it is raining or even when it is foggy outside, but when I am walking underneath an oak tree, and caterpillars are falling down I have a problem. Oak tree caterpillars are munching through the new spring growth of our trees throughout Central Florida. I am also seeing a large increase in the amount of leaf-rolling weevils present on our trees. In this article, I will go over the life-cycle of these insects and how you may be able to control them in the landscape. Let’s get started.

Tree caterpillars lay their eggs in mass on the tender new growth of oak trees. These caterpillars are the larval stage of the tussock moth. Normally, these caterpillars appear in late February and early March, but because of the cold weather we have been experiencing this year they are running a little late. As the leaves enlarge, the eggs hatch and the young larvae begin to feed. As they grow, their appetites increase. For those of us walking beneath the trees, or for cars parked under their shade, caterpillar fecal pellets can be more than just a nuisance. People can slip and fall on surfaces covered by these pellets and cars can have their paint ruined by its buildup. By the time you decide to rid your tree of these pests, their damage may have been complete. Your tree may have lost all of its leaves, but they will grow back. Repeated losses of foliage can leave your tree in a weakened state.

Even though many professionals state that control measures are unwarranted for these pests, trees weakened by leaf loss can lead to other problems. Professional applications of an insecticide before the caterpillars lay their eggs is your best option. This will also save you time and money cleaning up what happens after the feeding process. Once caterpillars have fed on the trees’ foliage, they drop from the canopy to complete their life-cycle of cocoon building. Several thousand cocoons attached to the home and/or outdoor furnishings can be unsightly and costly to remove, not to mention that the hairs shed by caterpillars can be irritating to people.

Scout your trees every spring and when these caterpillars are seen, you should seek out controls such as Dipel or Thuricide, which only kill caterpillars. For large trees, you will need a professional applicator that performs tree injection. This environmentally friendly service places products directly into the trees’ vascular system without any spraying. The good thing about tree injection is that the products will last a full year. You can have your trees treated before the caterpillars are present.  

Leaf Rolling weevils are also damaging our trees. These small red and black weevils attack the spring and summer flush growth of oaks. Adult weevils work their way up into the tree to a branch with new growth. Once a suitable leaf is found, the weevil will bite the midrib a series of times causing the leaf to bend and roll up on itself. As the leaf folds from the tip, the weevil deposits a single egg inside the rolled leaf then continues to fold the leaf around the egg. Enclosing their egg in these small one-half inch rolled leaf tips help to protect their young from predators. Thousands of these rolled tips (nidus) can be present giving trees an overall brown look. Some homeowners have called their service companies thinking their trees were dying. Although this infestation may look to be alarming, the tree is in no real danger unless other stresses have injured the tree.

Drought stress, insect pressure, diseases, and caterpillar defoliation can weaken trees making them susceptible to other more aggressive diseases such as Oak Tree Decline. Proper identification of these insect pests and controlling them prior to when the destructive stages of these insects can be unleashed, can save your trees and the aesthetic value your trees add to your landscape. Regular scouting of the landscape for any pests can give you a jump start in controlling insect populations. Enjoying your yard should be fun for the whole family and remember, without plants, we would not be here.

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