I have 4 very large arborvitae in my yard. This summer, I noticed that one of them was browning. I called an arborist who said it was dying, possibly from being too close to the others. He found no signs of disease or insects. I also consulted with the village arborist (who was here about another tree on the village right-of-way) who said the same. I had it removed. Now, I notice that the rest of the arborvitae are starting to brown. These trees form the border along my side yard, provide needed privacy and house abundant bird life. The only thing I noticed that was out of the ordinary when the tree was removed was a huge yellow jacket or hornet nest in the base of the trunk. Are all the arborvitae goners? Is there anything I can do and why, after all these years did this happen?