Found it! The Rev. William Archibald Spooner is apparently the source of the lines:

"I Saw a Butterfly flutter by...
Saw a Dragonfly drink a Flagon dry..."

As Spooner phrased it back in the late 19th century:

Now you see a butterfly
Bright and nimbly flutter by,
Followed by a dragonfly,
As it drains its flagon dry...

Source: Richard Lederer, Maine Sunday Telegram, 8/31/97

Cheerily,
Charley Noble