An entomologist at the University of Northern Iowa says spraying isn’t the answer to most mosquito problems, even if you fear West Nile. The virus is carried by the biting bugs, but only by one strain of the many kinds of mosquitoes there are, and biologist David Mercer said this week that clearing out breeding spots in your yard or “back forty” is one of the most effective ways to combat the bigs and the virus. Anything out there that holds water and collects organic material, for a short or long time, will be found and used to breed by mosquitoes. Some people looking for a natural alternative to chemical spraying have tried buying minnows to eat the immature mosquito larvae. Some are called “mosquito fish” and in fact are effective at controlling the bugs in some parts of the world — in the right circumstances, he says they can be very effective. As with any new species, Mercer says there can be a problem if the fish in turn are introduced to places where they aren’t native and don’t have natural enemies to keep them from taking over an ecosystem. Treehole mosquitoes are another variety that present a problem, but Mercer says cutting down forests is no solution. An intact habitat with birds and other flying mosquito-eaters can keep the number low, if not completely absent. Mercer says chemicals aren’t going to take care of the mosquito problem but there’s a lot people can do to remove breeding places and cut the number of the bugs.