Aerial mosquito spraying under way

Part of the Mosquito Research and Control Unit's strategy involves aerial operations over mosquito-breeding areas on Grand Cayman, Cayman Brac and Little Cayman.

The Mosquito Research Control Unit will begin its second treatment of mosquito swamp areas this week in a bid to stop nuisance biting. 

The research facility will use low-flying aerial operations to distribute pellets across 12,000 acres in Grand Cayman starting in West Bay, before heading to the north side of the island and then covering 320 acres in Cayman Brac.  

The aircraft applies small pellets designed to target mosquito larvae developing in aquatic habitats to prevent the occurrence of biting mosquitoes. Rain activates the pellets which provide mosquito control for up to two months.  

MRCU director William Petrie said there are usually three aerial operations each year, depending on the season.  

Dr. Petrie said this year there was a dry July with low tides but a wet August, with high tides. 

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“This season is a bit different from last year. We did our first application back in May and that went very well,” Dr. Petrie said. 

“We’re bringing the second treatment slightly forward in response to the rain and tides. The type of season we are having now we should be OK with three applications.” 

The operation was completed over 475 acres on Little Cayman last week due to elevated mosquito breeding. 

The low-level flight operations are completed May to November during mornings and late afternoon, with each treatment usually completed within 10 days, if weather permits.  

“They are synchronous so that instead of one or two, we get a mass emergence, because the eggs all hatch at the same time. We can go from having none to very few, then we get a mass emergence, they can be very numerous and cause quite a nuisance,” Dr. Petrie said. 

He said the mosquito population would be “potentially high” if left untreated. 

“We have quite a high number of species of mosquitoes for a small island, or a group of three islands that are highly isolated. We have 36 species of mosquitoes but most of them we don’t see all the time,” he said. 

The treatment stops nuisance biting from the Aedes taeniorhynchus, or swamp mosquito. This breed of mosquito does not carry dengue fever or chikungunya. 

The diseases are transmitted by the Aedes aegypti or Aedes albopictus mosquitoes, which are found in containers which hold water around houses.  

A third treatment will follow as the chemical activity wears off.  

For information, visit or phone 949-2557. 


The MRCU is conducting low-flying aerial operations across swamps to control mosquito breeding.
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