Tree care


I have noticed sawdust at the base of a tree in our front yard. There also is sap running from very small holes throughout many branches.What should I do?

I am located in Toronto. I’m unsure of the type of tree.


The holes, the sap and the sawdust are all indicative of an insect pest.  Your first step should be to identify your tree. This is important because there are a number of different insects known as “borers” that bore holes in tree trunks and branches in their larval stages, often producing sawdust residue as well as sap-filled holes. Many of these borers are specific to certain types of trees. Some create a sawdust residue, known as “frass”, and some, such as the Emerald Ash Borer, for example, do not. Carpenter ants, common in Ontario, can produce large quantities of sawdust at the base of a tree.

Most borers do their worst damage to trees that have already been stressed –indeed, insect borers seek out trees that have already been weakened. Stressors include under- or over-watering, existing disease, injury by mechanical equipment, bark damage by frost, etc.

A certified professional arborist can help you to identify both your tree and the pest, and can then recommend a course of action. To find an arborist in the Toronto area, visit the Ontario branch of the International Society of Arboriculture at

You mention that your tree is in the front yard. If it is a City of Toronto tree, you should contact the Urban Forestry department to report this. Here is a link to the City of Toronto directory with contact information for Urban Forestry: