Bacterial mosquito pesticide. Jar of the bacteria Bacillus sphaericus that are used as a biological pesticide to kill the larvae of Aedes aegypti mosquitoes. When the larvae eat the spores of this bacterium, a toxin is released that causes the larvae to stop eating. The larvicide is used in the stagnant water where the larvae are found. Mosquitoes are a vector (transmitting agent) for many diseases. A. aegypti are the main vector for the viruses that cause dengue fever. Pesticides are used to control mosquitoes in an effort to reduce the transmission of the dengue viruses to humans. Photographed in Cuba in 2002.