Fruit flies are known to eat the flesh of dead fruit, which has the ability to carry deadly pathogens such as the H5N1 flu.
However, the fruit fly that was found in a fruit salad in California was also capable of killing other fruit flies.
The Fruit Fly Identification Laboratory (FFIL) discovered the deadly strain of fruit fly in a salad at a grocery store on Wednesday.
It was also found in the food of a dog, the California Department of Public Health said in a statement.
The deadly strain was discovered after a customer at a nearby store spotted it and notified the authorities.
The department said the person who reported the fruit flies had been “unaware of the danger posed by the flies and did not have any symptoms.”
The FIL lab is working with the USDA and the state to develop a way to identify the fruit-fly killer.