Non-Chemical Control

After trees and shrubs are infested with borers, non-chemical controls are limited.

Remove and destroy (burn or chip) infested, dying or dead plants or plant parts, including fallen limbs. Severely infested trees ("brood trees") only produce more pests that can attack neighboring trees.

Several natural enemies attack insect borers, including predatory beetles, parasitic wasps or flies, and birds, especially woodpeckers.

Insert a flexible, small gauge wire into borer entry holes to puncture and kill the tunneling insect. Several attempts may be needed to be successful.

Use pheromone traps to monitor adult activity, and disrupt the mating and egg-laying of clearwing borers. These traps often only attract males.

Use ultraviolet blacklight traps to monitor adult beetles, which are drawn to the light and die in the bucket. These traps attract both males and females.

Chemical Control

Stressed, unhealthy trees may be repeatedly attacked and need repeated insecticide treatments. This is often expensive and not environmentally friendly. The first priority is to improve overall tree health, and use insecticides as a last resort. In addition, most chemicals can only be obtained and applied by licensed professionals with specialized equipment.

**Dursban, Sevin, or Ortho Borer and Leaf Minor**

Insecticide products registered for borer control are listed in table 1 below. Most of these products are applied as sprays to the trunks and branches, and are contact, residual insecticides (e.g., carbaryl, chlorpyrifos, lindane, permethrin). While these products do not kill larvae that have already penetrated the sapwood or heartwood, they will kill adults and larvae tunneling through the treated bark layer. These products are applied preventively and may be effective for 3 to 10 weeks.

Complete spray coverage of all trunk and branch surfaces is necessary for preventive control of borers. Treating only the base of the tree trunk is enough to protect the tree only from a few insects such as the black turpentine beetle and the peachtree borer. Thorough coverage may be difficult on large trees and may result in drift to non-target areas. To minimize drift, spray only on non-windy days. Read the insecticide lable for the proper protective clothing requirements.

Systemic insecticides are often ineffective for borer control and few are labeled for this purpose. Systemics may be applied as foliar sprays, root drenches, or trunk injections. Trunk injections work by delivering pressurized and concentrated insecticides into the tree. However, these injections are most effective against sap-feeding insects and rarely affect woodborer larvae. The process of injecting the insecticide through a narrow tube and into the drilled hole may result in sap staining, and could allow pathogens an entry point. Translocation of the insecticide is unlikely in partially girdled areas. The use of these products has not been studied in Florida.

Table 1. Chemical names, trade names, and formulations of insecticides available for professional use on trees and shrubs.