7023.      Clusters of these bugs appeared this week (August1) on various tree trunks. The picture is a medium sized cluster. Some trees had many clusters. We are wondering what they are and if they are harmful to the trees. Thank you. Apsley, Ontario. Canada

Number 7023. These are psocids (Psocodea: Psocidae) known as bark lice or tree cattle. They are completely harmless. Click here for more detailed information.