One of the most popular sugar substitutes on the market is also an insecticide -- masking the bitterness of coffee one minute, killing fruit flies the next.

Millions of people every day put the sweetener erythritol in their coffee and tea. Its consumers know it better by its slightly more appetizing trade name Truvia, in which erythritol is the main ingredient. No matter what it's called, the sugar substitute dramatically reduces the life expectancy of fruit flies.

According to a new study, published this week in the journal PLOS ONE, fruit flies that consumed Truvia lasted just 5.8 days. Flies that consumed other artificial sweeteners, or nothing at all, lived between 38.6 and 50.6 days.

"I feel like this is the simplest, most straightforward work I've ever done, but it's potentially the most important thing I've ever worked on," said senior author Sean O'Donnell, a professor of biology and biodiversity at Drexel University.

The idea to study Truvia's insecticide qualities was spawned by the son of O'Donnell's research partner.

"He asked if he could test the effects of different sugars and sugar substitutes on fly health and longevity for his science fair, and I said, 'Sure!'" said study co-author Daniel Marenda -- speaking of his son Simon, who became curious about the subject three years ago when he was in the sixth grade.

Erythritol, a naturally occurring sugar alcohol, has been approved as a food additive by the U.S. Food and Drug Administration, and extensive research has shown it to be safe for human consumption.

The scientists say more testing is needed to see whether erythritol could be used as a commercial insecticide.