Control With Predatory Nematodes
In cases where there are many borer tunnels and/or the tunnels are too crooked or inaccessible to insert a wire to kill them, a biological product, predatory nematodes, may do the job. Mix the powdered microscopic roundworms with water according to package directions and spray the slurry bark surfaces of infested limbs of the tree or shrub. The nematodes enter the holes and seek out the borers as hosts for their eggs, killing them.
Researchers have found the caterpillar nematodes, to be fairly effective biological controls for borers.

In tests, when these predatory nematodes were sprayed in solution on trees or shrubs heavily infested with borers, up to 85% of the borers were killed after 2 weeks. When the nematodes were sprayed directly into borer holes, borer activity was reduced by as much as 90 percent.