The mosquito life cycle includes an aquatic stage where they exist as larvae, often called “wigglers.” This phase lasts from four to 14 days, depending on water temperature. During this time, larvae constantly feed to store energy for the non-feeding pupal stage and their eventual emergence as flying insects.
Primary Food Sources for Mosquito Larvae
Most mosquito larvae are filter feeders, consuming microscopic materials suspended in the water or settled on surfaces. Their diet consists of microorganisms like algae, bacteria, protozoa, and yeast, along with organic detritus from decaying plants and animals. This food supply is common in stagnant water environments such as ponds, birdbaths, and water-filled containers like old tires.
To feed, larvae use specialized mouth brushes that move rapidly to create small currents, drawing food particles toward their mouth. Some species also scrape biofilms, which are layers of microorganisms, from underwater surfaces like rocks and vegetation. This feeding allows them to progress through four growth stages, known as instars, before they can pupate.
Predatory Larval Behavior
In contrast to filter-feeding, some mosquito species have predatory larvae. The most well-known belong to the Toxorhynchites genus, sometimes called “elephant mosquitoes.” These larvae are larger than other mosquito larvae and hunt the larvae of other mosquito species instead of consuming microorganisms.
This predatory diet provides the protein for the female to produce eggs in her adult life, eliminating the need for a blood meal. A single Toxorhynchites larva can consume hundreds of other mosquito larvae during its development. These larvae are opportunistic hunters, using mechanoreceptors to detect movement in the water before striking prey with their mandibles.
Exploiting Diet for Mosquito Control
Understanding mosquito larvae feeding habits is central to modern control strategies. One effective method involves using Bacillus thuringiensis israelensis (Bti), a naturally occurring soil bacterium. Bti is formulated into products like dunks or granules and placed in standing water. When mosquito larvae ingest the Bti bacteria, it releases a protein toxic only to them, destroying their digestive system. This method is specific and does not harm other insects, fish, birds, or mammals.
Another diet-related control method is source reduction, which involves eliminating the habitats where larvae thrive. This can be as simple as emptying containers that collect rainwater or regularly cleaning birdbaths and gutters. By removing standing water, not only are breeding sites eliminated, but the organic debris that serves as the primary food source for most larvae is also removed, preventing their development.