I have a nasty attack of trunk borer in a big hakea in my front yard.
please don't tell me to stick a piece of wire in a hole - there are attacks on multiple branches with no obvious borer holes
Is it an old Hakea? if so there isn't a lot you can do to stop any outbreak at this stage.
Re: Wire inserted method, borers like termites are very adept of travelling long distances through branches from an obvious entry point. Apart from the use of some nasty chemical use via injection there’s not a great deal of other techniques. Usual feeding/watering and pruning practices can also assist.
If it's caterpillar frass in webbing it may not be borers or the holes may be hidden under the webbing. Just remove the webbing when it occurs and the caterpillars or borers will have nowhere to hide from predators