scientists would release genetically modified male mosquitoes into the wild. that gene would make the offspring die. in brazil, scientists are already using these mosquitoes. our dr. richard besser saw them firsthand in february. >> it produces two million male mosquitoes. >> reporter: this comes as the centers for disease control warns zika could spread in the united states. mostly in the gulf, florida, and texas by june. zika is linked to birth defects in brain development. putting pregnant women at risk. while the experiment in brazil has proven successful, it doesn't sit well with some living in the florida key where is the insects would be released. >> when you open this pandora box, there is no way to recall the mosquitoes. >> reporter: critics fear with experimenting may not be safe. the fda is taking public comments before a final decision on the florida field test is made. tom. >> eva, thank you. >>> a record number of travelers hitting american airports this travel season as spring break approaches. right now airports are dealing with out of control