I was reminded a few days ago of their first invasion due to Facebook's memory feature. As if on que, I started to notice signs of them on the fence for the dog yard. Today, there were three of them clinging to Starbuck's back when I let her back in this morning. I wrote "clinging," but before I could wipe them off, she shook and the worms went flying to who knows where. Ugh, my skin is creeping just to think about it.
This invasion seems to happen after a period of hard frost followed by a slight warming with cold drizzle. It seems to end after a hard freeze. The snow cannot come soon enough.