As I walked past my truck I heard what I thought was the tapping of raindrops. It was rain alright......frass rain. What is frass you ask? Well to put it lightly it's caterpillar/larva crap. So in essence I was literally being crapped upon ;-) I looked up into the ash tree that my truck was parked under and could see something on its leaves. I grabbed one of the low hanging limbs and that's when I found the producer of the "rain". On just about every leaf on the limb were the larva of the blackheaded ash sawfly eating away as if there were no tomorrow. If you put them close to your ear you can almost hear the crunching of plant material in their famished jaws. I look at other leaves and I find more- the tree is inundated with them. Lined up in rows....feeding side by side......it was a scene of mass consumption.