The Mosquito Research and Control Unit (MRCU) continues to carry out extensive mosquito control operations across Grand Cayman following the season's first large mosquito emergence.
This emergence is an annual event typically associated with the start of the rainy season and was anticipated by MRCU. This year, mosquito production has been influenced by a combination of tidal flooding in coastal wetlands and recent rainfall, creating favourable conditions for mosquito breeding and emergence.
While mosquito numbers remain higher than what residents would consider comfortable, extensive aerial larviciding and ground-based control efforts carried out in recent weeks helped reduce the size and duration of the emergence. Without those proactive treatments, mosquito numbers would likely be substantially higher.
MRCU teams have been actively responding through a combination of aerial and ground-based mosquito control operations. However, weather conditions have presented significant operational challenges in recent days.
This week, wind, turbulence and precipitation have prevented MRCU from completing planned aircraft treatments. Pilots remain on standby and are prepared to take advantage of suitable weather windows as they become available.
MRCU is also currently operating with one aircraft temporarily out of service. While this does reduce operational capacity, the primary factor limiting aerial operations this week has been weather conditions. Once suitable flying conditions return, aerial treatments will resume using the Unit's remaining operational aircraft.
Weather conditions can also affect truck fogging operations. MRCU is unable to conduct aerial or ground based adult mosquito control treatments when rainfall is occurring, and product label requirements prohibit applications when wind speeds exceed prescribed limits.
Although aircraft operations have been limited, MRCU's ground teams have continued carrying out truck fogging operations whenever conditions allow. Truck fogging remains an important component of MRCU's mosquito control programme. However, trucks cover significantly less area than aircraft and are most effective when used alongside aerial operations.
Data collected through mosquito traps, field observations and reports from residents indicate that North Side, East End and parts of Central Grand Cayman are currently experiencing some of the highest mosquito numbers. Elevated mosquito activity is also being reported in other areas across Grand Cayman, and MRCU teams are deploying resources where surveillance data indicates they will have the greatest impact.
MRCU continues to conduct mosquito surveillance and control activities across all three Cayman Islands. While the current emergence is primarily affecting Grand Cayman, mosquito numbers in Cayman Brac and Little Cayman remain considerably lower.
Many of the mosquitoes currently affecting Grand Cayman originate from coastal wetlands and other tidal habitats. When these areas become flooded, large numbers of mosquito eggs hatch at the same time, producing mosquito populations that can affect communities across the island. Wind conditions can further influence where mosquitoes are experienced, carrying them well beyond their original breeding areas.
MRCU's work supports the Cayman Islands Government's 2026–2028 Broad Outcome of Health and Social Development by helping to protect public health and improve quality of life for residents across all three Cayman Islands.
To learn more, visit the MRCU website and social media platforms.