When I was an ornithology graduate student in Minnesota, I was afield year-round studying the behavioral ecology of Blue Jays. In the wintertime--which started in late October and lasted until at least mid-April--it was as cold as I could ever imagine (40 below, plus wind chill!), and I dressed out in longjohns, parkas, and insulated boots. I didn't mind the cold very much, since I usually raised a sweat while moving around my study site on snowshoes or cross-country skiis, but my binoculars did freeze up now and again.

When spring finally arrived in late April it was incredibly nice, but the niceness lasted only about three weeks. After that a far greater unpleasantry than blinding blizzards hit with substantial force.

In some ways, I hated to see winter go, because I knew as soon as the snow and ice melted Minnesota again would become the "Land of 10,000 Lakes," which also would make it the land of at least ten-hundred-million-billion mosquitos.

As a field biologist, I shudder at making an HVJ--a "human value judgment" (and my students will scold me for it)--but I must confess I see mosquitos as one of nature's major mistakes. I realize that lots of birds eat mosquito adults and that many aquatic organisms dine on their eggs and larvae, so these little insects obviously have a role in the ecology. However, I'm certain all the mosquitos in the world could be replaced by something that doesn't seek out every smidgen of my unprotected flesh with intentions of sucking out my precious hemoglobin and raising huge welts on my skin!

Some warm days in the field in Minnesota I just felt like crying. All I wanted to do was spend a little time stalking Blue Jays, and here the insect world was sending its peskiest blood-sucker to make me miserable. Even in summer I had to wear long sleeves, a hat, gloves, and a head net regardless of the heat, just to keep my sanity and my red blood cells. Things might have been better had I been deaf, because the constant hum of hovering mosquitos an inch from my ear did nothing to ease my anxieties about impending bites.

I distinctly remember dreaming in Minnesota about South Carolina's Piedmont, coveting those summer days when I could get up at dawn, pull on nothing but binoculars, a pair of shorts, and sandals, jam a field guide in my pocket, and go out for a four-hour bird walk with nary a mosquito bite to scar my hide.

South Carolina probably has just as much standing water as Minnesota--we might call our state the "Land of 10,000 Farm Ponds"--but the Piedmont is blessed with a relative dearth of those accursed mosquitos. At first thought it makes little sense, since a cold Minnesota winter should kill off the insects (it doesn't because mosquitos overwinter as eggs) and since the warmer weather here should (and does) provide a longer, more hospitable breeding season.

So what's the secret of fewer mosquitos in the Piedmont? It probably has nothing to do with those fogging machines that run around stinking up the neighborhood a few times each summer, and it probably isn't a result of insect-eating birds like Purple Martins and Barn Swallows, although they do help. What then could be responsible?

I'd like to bring to your attention a miniscule little creature to whom I plan to dedicate a major monument, that being Gambusia affinis, the Mosquito Fish. Gambusia (a name ironically taken from Spanish slang for "worthless") is a tiny fish that tolerates a wide variety of water conditions, including freshwater marshes, drainage ditches, sewage lagoons, and farm impoundments like Hilton Pond.

The male Mosquito Fish (above left) is about an inch-and-a-quarter long, with females a little less than twice that length, and each will--and I emphasize this with great admiration, respect, and gratitude--each will consume its own weight in mosquito larvae every day!

What a godsend these fishes be. A relative of the ubiquitous Guppy, Lebistes reticulatus, Mosquito Fish are live-bearers that can produce up to 60 young per mature pair every month or so from April to October; this period just happens to coincide with the time when mosquito eggs are hatching into larvae. Both sexes of Mosquito Fish are pale silvery-green like the Guppy, but differ in that they have small black spots on the fins. The male is recognized by his highly-modified anal fin (called a "gonopodium," or "gonad foot") with which he inserts a sperm packet into the female's vent for internal fertilization--rather uncommon among fishes. A single mating may be sufficient to supply sperm for several consecutive broods.

With upward-facing mouths, baby and adult Mosquito Fish cruise the water's surface, consuming great quantities of wriggling mosquito larvae that come to the top to breathe. They are native mainly to shallow waters of the southeastern United States, where some fishermen call them "potgut minnows," but they have been introduced in many countries of the world to control mosquito populations.

Unfortunately, and as usually is the case when we export or import flora and fauna, these pugnacious Mosquito Fish have wreaked havoc on many aspects of the ecology of foreign lands, primarily because they consume fish eggs with the same voracity they use on mosquito larvae. In Thailand, the Philippines, and the lower Nile valley they have completely wiped out several endangered native fish species, throwing other parts of the ecosystem out of balance. Even in this country, when stocked as food for largemouth bass in commercial hatcheries the Mosquito Fish quickly turned the tables and destroyed large numbers of bass eggs instead.

Fortunately, they fit into the natural scheme very well here in the Piedmont, and I am eternally thankful. I take great pleasure in sitting on the bank at Hilton Pond, knowing that every time I see a mosquito larva break the surface a Mosquito Fish mouth won't be far behind. One quick nibble and the number of potential biting insects on my property is reduced by one.

That doesn't seem like much, but I counted about 200 Mosquito Fish in one square yard of shallow pond water yesterday, and I know those finny little creatures are out there gulping down 'skeeters all day long, and maybe all night, too.

Let's hear it for Mosquito Fish!

Back to Piedmont Naturalist Volume 1 (1986)