What are borer insects?
Borer insects are usually the larvae of particular moths and beetles. The adults lay their eggs either on or in the bark of a tree and the larvae hatch and start consuming the tree.
Tell tail signs of borer insects are: leaves on whole branches dying off; holes in the bark; bark lifting off or falling off; and sawdust on the ground and/or on the trunk itself.
What can we do about borer insects?
There are many products on the market that promote the death of borers. These chemicals are unnecessary and are overkill. They do nothing to treat the problem – they only treat a symptom.
We can think of borer insects as a secondary issue. The key cause of a borer insect infestation is a sick tree. A healthy tree has healthy sap and this sap can surround and drown borer larvae. It’s a natural defence mechanism.
Therefore, if we can increase the health of a tree, we should be able to stimulate sap production and this natural defence mechanism. But does that actually work?
Case study of effectively treating borer insects
One of my commercial clients has a tree that had leaves on whole branches browning and dying off. My client suggested we might chop the tree down but I was reluctant.
That particular site is in the middle of an industrial area.
There are two significant gardens at the front and back of the site. The site itself is mostly concrete and houses approximately 34 businesses. It’s a business park of approximately 2-3 acres.
Because of the front and rear gardens, this site houses a number of native birds. One of which are the Superb fairy-wren – blue wrens. I love these little guys and I have noticed they tend to use the tree as protection. There are other small birds that also use this tree.
Therefore, I recognise this tree as key habitat for those birds. The tree is located in the middle of the site. It’s the only native tree in that vicinity and its surrounded by concrete. I’ve noticed that the wrens land there when flying from between the front and rear garden areas. I explained that to my client and they agreed that I could try to treat the tree rather than chopping it down.
The tree is surrounded by Lomandra longifolia – an Australian native clumping grass. When I cleared some of the Lomandra, I noticed that some of them were growing right next to the trunk. It also became obvious that the tree had fallen over at some stage. The trunk was actually horizontal.
There were a significant number of exposed roots. The horizontal trunk had small holes in it. There was a marked absence of bark – much of which was lying on the mulch underneath. I also noticed a fine woody substance like sawdust.
I concluded that we were probably looking at borer insects!
Remedy for Borer Insects
My aim was to increase the health of the plant so that it could deal with the borer insects itself. I cut off the dead branches. This relived the tree from the weight of the dead wood, thereby reducing stress. I also cut back and pulled out some of the Lomandra that was in the immediate vicinity of the trunk – where it met the soil.
To the exposed roots I added a compost mix and ensured they were completely surrounded by soil. I poked and prodded the compost into the exposed roots. Note that some composts are hydrophobic, so we may need to add an organic liquid soil wetter.
To the root zone and the surrounding top soil I also added some rock minerals and two types of soil conditioner: one fish based and the other seaweed based. I added a hoop pine mulch and watered the root zone well.
That’s all I did and it didn’t cost my client much at all.
Recovery after borer insects
Unfortunately, I didn’t map the recovery rate. But the tree has certainly recovered. It’s been about 18 months now but I recall seeing a marked improvement within 6 months.
Therefore, in my opinion, the key to helping a tree infested with borer insects is to help the tree to increase it’s health. This stimulates it’s natural defence mechanisms. This is the case with most plant health problems. Read my blog on sap sucking insects for more information.
Focusing on plant health is also a healthy and non-toxic process. It’s the key to creating organic gardens and healthy, organic ecosystems and can be applied successfully in commercial gardens…
Isn’t that interesting?