Does putting tape on my trees stop gypsy moth caterpillars?

In short, no.

Go for a drive in our state of Connecticut and you will see many trees which are standing dead having been killed by repeated defoliation from gypsy moth caterpillars.

Some of these dead trees still have duct tape on them from when the property owner tried to trap them as they crawled back up the trunk. Dead trees with tape on them pain the picture very clearly. If there are not many caterpillars the tape might work for you. If it works then there probably were not enough to warrant a health concern for the tree. If there is an outbreak, forget about it.

Two years ago as an outbreak began I was in Marlborough, CT to spray caterpillars for a customer of ours. The insects had just recently hatched and were still small. I sprayed all the trees on his property. As I left the neighborhood I noticed a homeowner had duct taped all the trees in their yard and had also put a sticky substance on it to further trap crawlers. About a month or two later I was back in the neighborhood and noticed the neighbor had no leaves, not on a single tree.

Flash forward to the following year and the duct tape was still on the trees only every oak tree in the neighbors front yard was dead. They may have saved a few bucks by trying to do it themselves. Now they can pay thousands upon thousands of dollars for removals and stump grinding. Don’t forget about topsoil and reseeding. They might be looking at about 10 grand total. Spraying would have been a drop in the bucket compared to that.