Mansonia larvae on water lettuce root

Water lettuce showing the fine roots

Almost all mosquito larvae swim in water and must come to the surface to breath air. The larvae of three mosquito species get air and protection from predators by attaching their breathing tubes to the roots of water hyacinth, water lettuce, and cat tail. Because they are in “permanent” water bodies, they are much less dependent upon rainfall than other species.

Where are the host plants found?

The exotic and invasive water lettuce and water hyacinth plants are usually found in slow or non-moving water bodies such as ponds and canals. Cat tail usually grows in ditches and along the edges of water bodies but can form floating “islands”.

Fierce Biters

The mosquitoes that emerge from these plant-host habitats are fierce biters. They search for a blood meal at dusk and stay active until about two hours after sunset. These mosquitoes occur in almost all areas of Sarasota County, but are most numerous in eastern rural areas that have ponds and waterways with these plants.

When These Species are Active

Two root-breathing species occur year-round. Numbers of the third species peak in the spring and fall months. These large brown mosquitoes can transmit Eastern Equine Encephalitis virus (EEE) to humans and horses. Fortunately, human cases are rare in South Florida, and there is a protective vaccine for horses.

What Can Be Done?

Controlling the plants that “root breathing” mosquitoes live on (source reduction) is the most effective way to control these mosquitoes. Waterways choked by the host plants must be carefully managed by state-certified professionals. Citizens can help by disposing of exotic aquarium plants properly and using only native plant in water gardens.

Aquatic Plants and the Law

Water Hyacinth (Eichlomia crassipes) and Water Lettuce (Pistia stratiotes) are both Prohibited Aquatic Plants under Florida Law (Chapter 5B-64 Florida Administrative Code). It is not legal for a business to sell water hyacinth or water lettuce in Florida. In fact it is against the law for anyone in Florida to possess either of these plants without a permit. That means that anyone collecting these plants from the wild or anyone with even a couple of plants in a water garden on their property are in violation of State Law. Please contact the Florida Department of Agriculture and Consumer Services (FDACS) for more information.

Past Pest of the Month

Lawn Mole
Lovebug		Root Breathing Mosquitoes and Aquatic Plants
Brazilian Pepper Tree		Bed Bug
Non-biting Midge		Widow Spiders
Red Fire Ant		Caribbean Crazy Ant