“Two silkworms were in a race. They ended up in a tie”

A popular “tie” pun is:
 
“Two silkworms were in a race. They ended up in a tie.”
 
The silkworm joke has been cited in print since at least 1975.
 
       
Google Books
Computers and Programming:
A Neoclassical Approach
By Peter Olivieri and Michael W Rubin
New York, NY: McGraw-Hill
1975
Pg. 253:
“I’m sorry I’m late, class,” he began, “but on the way over here from the parking lot I stopped to watch two silkworms having a race. They ended up in a tie!”
 
15 March 1976, Detroit (MI) Free Press, “Yes, Clock Cheated Wolverine Cagers” by Joe Falls, pg. 1-D, col. 1:
The Almighty Swami: “Did you hear about the two silkworms who chased after a lovely girl silkworm and wound up in a tie?”
 
Google Books
PUNishment:
The art of punning or how to lose friends and agonize people
BY Harvey C Gordon and Rand Kington
Glenview, IL: Punster’s Press
1977
Pg. 17:
Two silkworms were once having a race. However, they ended up in a tie.
 
8 October 1978, Boston (MA) Globe, “My Favorite Jokes” by Harvey C. Gordon, Parade magazine, pg. 30, col. 4:
Two silkworms were once having a race. However, they ended up in a tie.
 
Twitter
Studiolit‏
@Studiolit
Two silkworms were in a race. They ended up in a tie.
1:12 PM - 18 Jul 2008
 
Twitter
Michael Klobe‏
@klobetime
Two silkworms were racing; they ended up in a tie.
9:11 AM - 9 Oct 2008
 
Google Books
5,000 Great One Liners
Compiled by Grant Tucker
London, UK: Biteback Publishing Ltd
2012
Pg. ?:
Two silkworms had a race–it ended in a tie.
 
Reddit—Jokes
Two silk worms were in a race…
submitted April 12, 2013 by [deleted]
It ended in a tie.
 
Tearable Puns
Jun 23, 2014
Two silkworms had a race.
Two silkworms had a race. They ended up in a tie.
 
Reddit—Jokes
Have you heard of the two silkworms that were in a race?
submitted June 27, 2017 by pizzafoIder
They ended up in a tie.