The spider-web thing in your tree is tent caterpillar. This is not a serious pest but the webs are unsightly. If you can reach them prune them out or knock them out of the tree. Make sure you have a trash bag nearby for disposal. B.t. (Bacillus thuringiensis) can be used for control but only early on when the caterpillars are young. As they mature it is not effective. You would need to penetrate the bags with the spray. For additional information see the information from the 'plant diagnostic' section of our website, http://plantdiagnostics.umd.edu/level3.cfm?causeID=1163

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