The State of Florida, USA, have been releasing around 6 million sterile flies each week to eradicate a disease that has killed just over 100 Key Deer. Screwworm was last experienced in that region in the 1960’s before making its alarming return.

The worm is laid on the deer before burying itself in the flesh, essentially eating the animal alive. This can also spread to livestock- which is hugely concerning for officials- and in rare cases, humans.

To battle the pest scientists have been breeding flies and releasing them into a giant chamber before inflicting waves of radiation upon them. This in turn leaves them sterile, meaning that when they are released they mate with female flies without being able to breed.

This technique was used widely back in the 1960’s to rid the flies from Mexico, Central America and the Caribbean. Pamela Manns of the US Department of Agriculture (USDA) said, “We don’t know exactly how long this process will take, but eradication efforts like this can last four to six months. It is not uncommon and we expect that to be the case here.”

The flies are still present in South America, however for the last 40 years the USDA has managed to keep a buffer zone. Officials are unable to say exactly how the flies have returned but as Florida is a central hub for tourists and inter-continental travel, it is always at some risk of disease.