This is from another discussion on another board about using protozoa to control misquito populations. Elaine chimed in with some interesting information and maybe some contacts to follow up on. Please read below, I had never thought of this issue from this direction Protozoa eat the young larval stages of the mosquito. In good water with lots of air, the protozoa best at eating all that zooplankton type of life are the flagellates and amoebae, along with a few ciliates. When water gets stagnant, the flagellates and amoebae diminish in numbers and activity. Only protozoa are left, but when water gets really bad, not even the ciliates are left, and that is when mosquitos get to be really bad. Fish fry - the youngest stags of fish after they just hatch - are also really good at eating mosquito larvae, and eggs too. But again, if water is stagnant and putrid, i.e., anaerobic, then these biological controls measures are non-existent as well. Algal blooms are significant players in this, and work by Steve Carpenter at the Univ. of Wisconsin showed, back some 15 or 20 years ago, that algal blooms are the result of losing the zooplankton, which of course, includes both the groups I was pointing out above. The zooplankton were lost, in the case of Lake Mendota, because the fish that consume the things that eat the zooplankton were being eaten by the sports fish that the US Fish and Wildlife were stocking the lake with. They stopped putting in pike and European trout (don't ask me the species, I'm not a fish person), and allowed people to take any and all of those species when they caught them, but the native sunnies, and a different trout and something else had to be released. The population of fish that eat the fish that eat the zooplankton rose back to pre-European levels, the zooplankton now started consuming mass quantities of algae, and there was no algal bloom on the lake again. As a student, I remember being able to walk across the lake on the algal mat that bloomed every summer. The smell mid-summer from the lake was awful when you sat at the beer garden at the Univ of Wisconsin, which is right on the lake. And the mosquito problem was notable, even for a place like Wisconsin, where the state bird is the mosquito................. I remember professors saying that algae PUT oxygen into the water, so how could the algal blooms be causing a problem? Think it through.................. Think you have the answer? then read on....... Sunlight only penetrates one or two cells depths when a mat starts to develop. By the time a mat is thousands of cells thick, the cells on the bottom of the mat are no longer alive, and the bacteria grow so fast on all that dead sugar-containing algal material that the bottom side of the mat goes anaerobic by the time the mat is just maybe 10 to 100 cells thick. Expand that problem over the whole of one end of the lake, and you can imagine the smell. and the mosquitos happily eating all those bacteria and getting to adult size in no time flat....... Steve got the USDW to change the fishing regs, and within one summer, the algal blooms practically disappeared, and the mosquitos are now just normal at the beer garden....... If an effort was made to add the necessary organisms to the lake, if the regs would prevent people from using chemical fertilizer to the lawns around the lakes and streams, the even those few mosquitos would likely not exist either? What would birds eat? Worms. all those worms that would be back in the lawns, where they are supposed to exist........ but can't because of the toxic level of chemicals poured on those lawns. OK, we are all working on putting an end to that insane amount toxic material going on soil, right?