PCMCD has an Aquatic Weed Control Program. We do not control weeds for beautification purposes. We only attempt to control invasive, non-native weeds that harbor certain mosquito species, or to thin out areas such as floating plant mats where growth is so thick that natural predators (e.g. minnows) can’t access the mosquito larvae and pupae.

Our aquatic weed control equipment includes herbicide trucks with a hose reel, two airboats, two Argos and even the helicopters can be outfitted for treatments. In some circumstances, the Aquatics teams may utilize the helicopter to maximize our control efforts. The continued development of residential housing in formerly unpopulated areas of the District results in a continuous increasing weed control effort.

Our primary efforts include the control of two exotic floating weeds: Water Hyacinth (Eichornia crassipes) and Water Lettuce (Pistia stratiodes). These plants support the development of Mansonia dyari and Mansonia titilans. A third mosquito, Coquilletidia perturbans, is also associated with aquatic weeds. It is found on a number of types of rooted plants along the edges of lakes, ponds, canals, and ditches but is best known to be associated with Cattails.

The larvae of these three species attach to the roots of the weeds with a modified air tube. They extract oxygen and nutrients from the weed itself minimizing their time at the surface of the water where conventional larvicides would be applied. Consequently, they are difficult to detect by both their natural predators and by mosquito control technicians.

To find the plant communities that support these mosquitoes, several techniques are employed. When Mansonia and/or Coquilletidia adult mosquitoes are collected in a Pasco County trap, which are placed throughout the District, we have an idea of the general location of the larval site. Our field personnel will then search for species of weeds known to harbor these mosquitoes. If necessary, the suspect area may be searched using a helicopter. Once the target weed species are found, herbicides are applied which will kill the weeds, reducing mosquito population numbers that are out of balance with nature. Because we do not target all floating plants, those that may exist on native vegetation can continue with their natural functions in our ecosystem.