geographic_location: Houston
Question: I have about 5 large live oaks in my front yard. There is one are about 10' in diameter that is emitting a residue that I have never seen before. This area is above my concrete driveway so this could be why I see this but there are plenty of other areas where the concrete drive is under the trees and I do not notice this. Daily, for about the last week I have seen hundreds of peppercorn sized items in this area. When you pick them up they turn to a granulated powder. They stain my concrete. The also have a ribbed texture prior to them breaking up. If they get wet, they kind of dissolve. Any idea what this is? I was wondering if it was a type of pollen that occurs this time of year. Is there a difference in appearance between a male and female tree pollen? I was trying to figure out if this was anything invasive on the tree to be concerned about.

Answer:This is definitely caterpillar droppings. No doubt. They must be big 'uns, though. I have lived under the canopy of the oak trees for too long not to recognize caterpillar excrement and the staining of the concrete is the tannin in the excrement. I have never had it this bad in the fall of the year. This life cycle will soon change and the problem will cease to exist.