Today, a cooler day, they were there again, this time clustering on grasses and on the trunk of a tree.
I found out their name by asking a man who was spraying weeds in the park. (How much work goes into maintaining these parks that Penny enjoys!) I thought the name sounded scary, but he said they're harmless.
And he was correct. Here's an article about these beautiful but strangely-named creatures. They are nectar drinkers.
This one had the nerve to land on Penny's toy!