Trees can become vulnerable to diseases and pests when damaged by boring bugs or birds. When this happens the tree itself is in danger of stunting or even dying. While tree professionals can assess the problem and recommend the best treatment options, you can save money and guarantee the work's quality by patching the tree yourself. All that is necessary are some basic observations and a little common sense.
Check the tree's crotch for holes. Holes can be as small as a dime, or as large as a tennis ball, depending on the pest.
Kill the pests. Poke a thin piece of wire into the hole and swish it around. This will kill any larvae living in the hole. If birds are the culprits, either remove the nest yourself and relocate it to a better location or contact animal control for assistance.
Prevent further infestations in the hole. Inject insecticide into the hole until it begins to leak out and stuff the hole with diatomaceous earth. The insecticide will kill any eggs or larvae that survived the wire stabbing and the diatomaceous earth will kill any pests that hatch after the hole is patched.
Seal the hole. Fill the hole with plumber's putty by pressing it into the hole with a putty knife. Continue pressing putty into the hole until the hole is filled and no additional putty will fit into the hole.