The majority of control activities take place on the Fraser River corridor during the spring freshet. Rising water in low-lying areas allows for the development of mosquito eggs laid in previous years.

Monitoring for the presence of larvae is critical, as biological controls only work at the larval stage. As water levels rise, a method called dip-testing is performed at larval-development sites to estimate larvae density which indicates if / when treatment is required.

Treatment consists of hand or helicopter applications of Bacillus thuringiensis israelensis (Bti). Bti is a microbial larvicide that is target-specific, non-residual and non-toxic.

All known mosquito development sites are GPS mapped and stored within a database in order to facilitate accurate annual monitoring. This database is continually updated with newly found development sites. Communications with the public assist staff with finding new sites.