Hordes of Boxelder Bugs - Oh My! (Updated)

(See update at the end of this post.)

As I drove into the garage after work this evening, some dark areas under the picture window at the front of our house caught my eye. I couldn't think what they could be -- from a distance I wondered if some dark ivy was suddenly growing up the brickwork. When I approached, I could hardly believe what I was seeing: thousands, surely, thousands of boxelder bugs. Take a look.

We routinely do get clusters of boxelder bugs on our south-facing house, especially on sunny fall days following a cold spell. I've taken photos and written about them before: in October 2007 and in October 2009. I've never seen swarms anything like what I saw today, and certainly never such huge swarms in the spring. This is such an odd season -- today, a rainy day in the 50s, would normally be a warm day for the second week of March. Instead, it was a relatively cool day in a string of days in the 60s and projected to reach 70 later this week. No wonder the insects are behaving strangely.  Maybe we'll have frogs and locusts next.

Here's a short video clip of this extraordinary sight.



Update, March 14: At about 10:30 yesterday morning when I stopped at home briefly, the large clusters were still there, looking very much as they did above. However, the sun was shining fully on the bugs in the left-most clump and there was a lot of activity, with bugs crawling over each other predominantly in a downward direction toward the ground. The clusters that were still shaded were completely still. When I returned at around 5:00 the clusters had completely dispersed. There were still some bugs here and there on the front of the house, but there were no longer any clusters.