On July 8, 1939, prior to the first game of a doubleheader with the Red Sox at Yankee Stadium, a horde of Japanese beetles formed a wall in front of the home dugout. Over 5,000 insects were captured in the process of fending off the insects, however, the problem would return later in that same month.

Home dugout? Obviously Red Sox fans.
v
Clearly — the only explanation that makes sense.
Japanese beetles are nothing if not persistent.
Truth.