Voters in a Florida county were at odds on a ballot referendum this past Tuesday about whether to allow the first trial of mosquitoes genetically engineered to reduce populations of the species that spreads Zika.

That species, the Aedes aegypti, lives in homes and is difficult to root out with insecticides. In addition to Zika, they spread yellow fever, dengue and chikungunya.

In Key Haven, the town where the trial could be conducted, more than 65 percent of voters rejected the plan. In Monroe County, which includes Key Haven, more than 57 percent of voters said yes.

The ballot measure, sometimes referred to as a “straw poll,” is nonbinding. A decision on the question will be made by the Florida Keys Mosquito Control District Board, which is scheduled to meet Nov. 19 to discuss the poll results and the results of five other surveys.

Oxitec, the company that developed the experimental mosquito, is owned by Intrexon Corp., a biotechnology firm focused on synthetic biology.

If the trial proceeds, the Britain-based company’s mosquitoes would be released three times a week over the small peninsula. Key Haven has just 1,000 residences and a single gas station. The native mosquito population is insulated by the ocean and the main highway, making for a perfect trial location, Oxitec said.