Okay, imagine that there are some tiny living things called "bacillus thuringiensis israelensis". They are like little soldiers that help protect us from bad bugs called mosquitoes that can make us sick.
These little soldiers have a special weapon called a toxin that they use to kill the bad bugs. But don't worry, the toxin only works on specific bugs like mosquitoes and doesn't harm humans, pets, plants or wildlife.
Scientists have figured out how to make lots of these little soldiers and use them to spray in places where mosquitoes live, like ponds or other bodies of water. When the mosquitoes go swimming, they eat the little soldiers and BOOM, their tummy gets upset and they die.
This helps keep us safe from getting sick from mosquito-borne diseases like malaria, dengue fever and Zika virus. Pretty cool, right?