Treatment for larval mosquitoes occurs only when problem species of mosquito larvae are found in large numbers. This involves constant monitoring of mosquito larvae habitats. Heavy rainfalls and exceptionally high tides can cause high increases in larval populations, which will soon advance to the adult stage where they become problems for humans.
Spraying for adult mosquitoes occurs only after the targeted species of mosquito has reached a point where they have become a documented problem. In order to spray for mosquitoes, certain types of mosquitoes must be found in significant numbers.