I have a large tree next to my house in the Atlantic City, NJ area. A couple of weeks ago I noticed a small (roughly golf ball sized) hole in the middle about five feet off the ground with what looks like sawdust at the bottom, which makes me think some type of insects are eating into the wood.
I washed away the sawdust and sprayed some bug spray into the hole. After a few days, the sawdust reappeared again. I was thinking of spraying something into the hole to seal it from any more "invaders," such as expandable foam.
Would this work and do you have any other (better) ideas?
Looks to big for an insect but also looks like a borer has entered the hole and left the sawdust. Most household insecticides will not kill a borer--they will not penetrate the woody tissue where the insect is living. The recommended insecticide is Merit or Onyx.. Spray the are around and in the hole and this will kill the insect. The foam will close the hole but it will also slow down the healing process. The tissue around the hole will seal off any fungi that gets on the wound. the foam will slow this sealing process. I would just spray the hole with the insecticide. These will not kill the tree so it is not as bad as you might think. The worst that could happen is a decay fungi gets into the woody cells and over many. many year causes the tree to become hollow. Pines secrete sap and resin and this decay rarely happens.