The Pasco County Mosquito Control District has an Aquatic Weed Control Program. We do not control weeds for beautification purposes. We only attempt to control 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 find the mosquito larvae and pupae.
Our primary aquatic weed control equipment includes an herbicide truck with a hose reel, two airboats, a Jon boat, an Argo and a tank truck which is used for herbicide applications and as a “nurse truck” for filling the spray tanks on the boats and helicopter. In some circumstances, the Aquatics team 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 tittilans. 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.
We only attempt to control plants that harbor certain mosquito species, or to thin out areas such as floating plant mats where growth is so thick that natural predators can’t find the mosquito larvae and pupae.
The larvae of these three species attach to the roots of plants with a modified air tube. They extract oxygen from the plant 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 suction trap which are placed throughout the District, we have an idea of the general location of the larva 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, effectively reducing mosquito population numbers.
Controlling the invasive non-native weeds helps suppress a mosquito population that is 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.