Thousands of genetically modified mosquitoes were released in West Bay on Thursday, kicking off what the Mosquito Research and Control Unit and collaborator Oxitec call their “Friendly Aedes aegypti project.”

The project, which was supposed to begin July 14, was delayed by two weeks after opponents of the initiative took legal action to try to halt the release.

On Tuesday, a judge refused a judicial review of the decision that permitted the import and release of the mosquitoes, and refused to grant an additional stay pending an appeal.

West Bay residents Giselle Johnson and Heidi Groves, who are part of the project’s laboratory and fieldwork teams, were to release 20,000 mosquitoes outside the West Bay Public Health Clinic on Thursday morning. The task, it turned out, was quite simple: opening 20 small plastic containers, each of which contained 1,000 mosquitoes, and shaking the flying insects out so that they might fulfill their purpose of sharing their self-limiting gene with wild female Aedes aegypti mosquitoes.

Since they will contain that self-limiting gene, the offspring of the genetically modified males and the wild females will not reach adulthood, thereby reducing the population of the mosquito that is responsible for carrying diseases like dengue, chikungunya and Zika.

“It is important that we are able to get on with the job as there is an urgency from the public health perspective,” MRCU Director Bill Petrie said in a press release. “We need to get the project back on track and put in place the preventative measures we have planned to reduce the risk of local transmission of mosquito-borne diseases.”

The rollout of the mosquito project will continue Friday and for the next several months in a 300-acre area of West Bay between Watercourse Road, Powell Smith Lane, Rev. Blackman Road and Hell Road. One hundred to 200 pots, each containing approximately 1,000 genetically modified, non-biting male Aedes aegypti mosquitoes, will be released around three times a week through a fan from a van.

At the release Thursday, Mr. Petrie said he wanted to remind people that the release is starting in West Bay because the district is a “hot spot” for Aedes aegypti mosquitoes.

The treatment phase in West Bay will continue for approximately nine months and will be rolled out to other areas of Grand Cayman after receiving the relevant approvals. Cayman Brac and Little Cayman are not affected by the Aedes aegypti mosquito.