City Mosquito Control Program Monitoring Underway
April 14, 2026
The City of Portsmouth’s Mosquito Control Program began monitoring on April 8, 2026. The City has contracted with Dragon Mosquito Control, Inc. to check swamps, salt marshes, woodland pools, ditches, catch basins and other shallow, stagnant water for mosquito larvae.
Citywide spraying for adult mosquitoes is not planned. Any decision to conduct emergency spraying of adult mosquitoes on City-owned property is made by City officials in collaboration with Dragon Mosquito Control and is based on mosquito surveillance data, disease test results, and weather conditions. Diseases such as Eastern Equine Encephalitis (EEE) and West Nile Virus are generally found in mosquitoes during the latter part of the summer and early fall. Residents will be advised in advance if spraying is planned.
When mosquito larvae are found, treatment may occur using one or more of the following:
- FourStar Bti CRG (Bacillus thuringiensis israelensis 10%)
- VectoBac (Bacillus thuringiensis israelensis 2.8%)
- VectoBac 12 AS (Bacillus thuringiensis israelensis 11.61%)
- VectoMax FG (Bacillus thuringiensis israelensis 4.5% & Bacillus sphaericus 2.7%)
- VectoPrime FG (Bacillus thuringiensis 6.07% & methoprene 0.10%)
- Natular (spinosad 2.5%)
- Altosid (methoprene 5%)
- BVA 2 Mosquito Larvicide Oil (mineral oil 97.0%)
- SunSpray MLO (mineral oil 98.8%)
Residents who own wetlands and want to opt out of any treatment can sign up with the No-Spray Registry at dragonmosquito.com/no-spray-registry or write to Dragon Mosquito Control, Inc., P.O. Box 46, Stratham, NH 03885. When writing, residents should include name, physical address, phone number and the color of the house.
For more information on spray dates, location, materials used, precautions or other concerns, call 603-734-4144 or email help@DragonMosquito.com
