The First Computer Bug Reported - There Really Was a Bug in the System!

The First Computer Bug Reported - There Really Was a Bug in the System!
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The Million Dollar Question

One of the most famous episodes of Who Wants to be a Millionaire? featured a man who got to the million dollar question and still had the ‘phone a friend’ option left. The question was about the first computer bug reported, and the four choices were for what type of insect it actually was. The contestant used his ‘phone a friend’ option to call his father but instead of asking help for the question, he told his dad that he was about to win a million dollars. The crowd roared and applauded, and the look on Regis Philbin’s face was priceless. The man then selected an answer, declared it to be his final answer, and walked away with a million bucks.

Many people in the IT field who have taken computer classes may have heard of this story about the first reported computer ‘bug’ actually being an insect that got inside a computer system and caused trouble. In this article, we’ll learn more about the incident and how the term ‘computer bug’ was coined.

Grace Hopper and the Moth

When software doesn’t work properly, we say that it’s buggy. The term de-bug is used to describe the troubleshooting process used to correct software problems. Even some software updates and patches are called bug fixes. The association with bugs and electronics/computers has been around for decades, and its origins are rather fascinating. Thomas Edison used the term over a century ago when discussing problems in electrical circuits.

The first documented case of a real bug inside a computer took place in the 1940s when researchers at Harvard University discovered a moth inside a computer system there. To understand why a moth would cause so much trouble, you have to know how computers were originally designed.

The first computers were nothing like what we have today. Back in the early days of computing, they were built using a series of vacuum tubes and relays, and the computer could be the size of a house. These giant contraptions were made up of devices that looked like something out of a bad sci-fi movie, but those building blocks lead to the powerful desktop or laptop you have at home now. An incredible amount of work was needed just to do simple mathematics problems on the first computerized adding machines, but you have to understand that the idea of a machine doing computations was truly revolutionary for the time.

In addition to all the components we might consider archaic now, those giant computers also used a lot of light bulbs, and this attracted bugs–especially moths. As such, they were extremely sensitive to outside interference, and their size made the likelihood of problems even worse. It was Grace Hopper, a pioneer in computing and programming as well as a Rear Admiral in the U.S. Navy, who discovered the bug and documented the incident. The image shown here is from her actual log book, and she taped down the bug that was discovered between the relays in the system.

What’s funny about this story is that the term ‘bug’ was around long before this real bug was discovered. This famous incident can now be found in countless textbooks and shows how some phrases can stick. Before those Harvard engineers could get their computer working again, they had to get the bugs out–literally.

Word Origins

Bugs aren’t the only things blamed when it comes to technical difficulties. When someone speaks of gremlins, the first image that comes to mind are the little green monsters that ruined Christmas in the ’80s movie of the same name. The origin of gremlins comes from British pilots in the 1920s who used the term to blame mechanical issues with their aircraft. Gremlins were also a very popular scapegoat during World War II, and the name is still used today to describe problems when the root cause isn’t immediately known.

It’s funny how words and phrases become part of the vernacular over the years. In this case, an actual bug helped to solidify a phrase that is still used decades later because it’s simple to use and offers an easier explanation than the overly technical reasons why a software or hardware problem occurs. It also makes for a good catch-all excuse for developers when something doesn’t work right, like when they tell you that the bugs are still being worked out.

Had the moth not been found inside that early computer system, I wonder how well the term would have stuck around. Instead, we might be talking about gremlins in our computers instead of bugs.


Smithsonian Museum of Natural History, “First Computer Bug, 1947”, retrieved at

Danis, Sharron. Rear Admiral Grace Murray Hopper. From The History of Computing, courtesy of the Department of Computer Science at Virginia Tech, retrieved at

Image credit: Wikimedia, U.S. Navy (public domain)