Mosquito Control

The Mosquito Control Program begins monitoring on April 11, 2022 in the City of Portsmouth. Crews from Dragon Mosquito Control, Inc., the City’s contracted service, will be checking swamps, salt marshes, woodland pools, ditches, catch basins and other shallow, stagnant water for mosquito larvae.

When mosquito larvae are found, treatment may occur using one or more of the following:

  • VectoBac (Bacillus thuringiensis israelensis 2.8%)
  • VectoBac 12 AS (Bacillus thuringiensis israelensis 11.61%)
  • Fourstar Bti CRG (Bacillus thuringiensis israelensis 10%)
  • Natular (spinosad 2.5%)
  • CocoBear MLO (mineral oil 10.0%)
  • BVA 2 Mosquito Larvicide Oil (mineral oil 97.0%)
  • SunSpray MLO (mineral oil 98.8%)

Citywide night-time road 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 based on the mosquito surveillance data, disease test results and weather conditions provided by Dragon Mosquito Control. Diseases such as 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.

Residents who do not want their property treated may use the No-Spray Registry online at or write to Dragon Mosquito Control, P.O. Box 46, Stratham, NH 03885. Be sure to include your name, physical address, phone number, a description of your house and acreage. If you have wetlands on your property and you would like Dragon Mosquito to check it for mosquito activity, email or contact them through their website at and request a survey through the Contact link. There is no charge for this service.