Weeds and wildflowers, and other visitors

Our front yard in Gloucester, as those who have visited us know, is really more meadow than lawn, as we mow it infrequently and allow (and in some cases even encourage) some wild plants to flourish there. One which has been spreading in recent years is something that I was eventually able to identify as brown knapweed, and I've been feeling lately that we're perhaps allowing it to spread a little too much, although it does have attractive purple flowers. But earlier this week I discovered that ( it has its uses... )

Wouldn't you know...

...that one of the few 90F days we get this summer would be the day of a contra dance?