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Cayman: MRCU Larviciding operations in progress

Grand Cayman, Monday, 22 May 2023 –  The Mosquito Research & Control Unit (MRCU) would like to advise the public that its Pre-Hatch Treatment, the annual larvicide application that takes place before the start of the first major rainfall event of the year, is currently underway.

“The Pre-Hatch Treatment allows us to apply larvicide products to known breeding sites with the intent of killing mosquito larvae when they hatch after flooding,” explains Dr. Alan Wheeler, Director of the MRCU.  “We use two main products: methoprene and spinosad, both of which are biorational products.  These are applied as pellet formulations to the mosquito breeding areas during MRCU aerial operations,” Dr. Wheeler adds.

Biorational products are low-impact substances or products that are typically biologically derived.  This means they have relatively low toxicity, and cause relatively little damage to the environment.

MRCU’s Pre-Hatch Treatment is a preventative control method, killing the mosquito larvae before they can develop to biting adults looking for a blood meal.  Due to the nature of this operation, larviciding only takes place during daylight hours and requires several passes of the MRCU airplane over a particular area.

“Mosquitoes emerge when the eggs are submerged and hatch after flooding, this may be by high tides or rainfall,” Dr. Wheeler continues. “It is important that the community understand that MRCU cannot control these events. By conducting preventative control operations- such as larviciding- we can minimize the number of adult mosquitoes emerging. However, MRCU supplements this work by also conducting its adulticidingoperations as a responsive control measure to quickly control biting mosquitoes. Adulticiding operations, which only happen at dusk or in the evening, can take several days based on the size of the emergence,” he concludes.

The Pre-Hatch Treatment has already been completed for the Sister Islands, and began in Grand Cayman on May 17th.  It will take the MRCU team 10-14 days to complete the treatment, depending on weather and resources.

For more information or to file a mosquito related complaint, contact the MRCU on 949-2557.


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