Transcript for Modifying Mosquitoes to Fight Zika Virus

New twist this morning in the zika crisis. With fresh cases emerging this morning, experts are now doing a version O fighting fire with fire. Can a new breed of gentlemen nenically altered mosquitos stem this tide? As we prepare to head into the height of mosquito season, the threat of zika virus continues to grow. This morning, scientists are fighting back. Using the mosquitos themselves. This morning, the fda is moving ahead with an experiment intended to help control the mosquitos that are in the U.S. Scientists using the insect itself. Creating a line of genetically modified mosquitos that will die before it can bite anybody. In two to four days after we release it, it will be dead. Reporter: Dr. Richard Besser saw them in February. This producesmillion male mosquitos each week. Reporter: They're altered so their offspring will die before they can transmit the disease. They said they're all male. Males don't bite. I hope that's the case, because there's 245,000 of them. Reporter: Since the start of the study, the number of mosquitos to spread the disease has gone way down. Critics worry that messing with genetics may not be safe right now. The fda is asking for public xhenlts on this. After that, the mosquitos could be approved for use. Very controversial. There's no guarantee this will work. They have some answers. Not all. Thank you, Eva. We want to send things to Ron and Ron, you're tracking a

This transcript has been automatically generated and may not be 100% accurate.