By Tom Baird
Salt marshes are the predominant coastal shoreline community from St. Joseph Bay to Tampa Bay, and St. Joseph Bay has about 762 acres of salt marsh fringe. Our salt marshes are some of the most productive areas on earth and are home to a myriad of fascinating plants and animals. There is one animal associated with salt marshes however that the Chamber of Commerce would just as soon not be mentioned. Tourist Development Councils don’t extol this animal’s beauty or friendly nature. But residents and visitors to Florida know it well. That is the little, I mean tiny, biting fly we know variously as sand flies, no see-ums, punkies, or biting midges. On a cloudy, breezeless day or at dawn or dusk they can drive you nuts, and unlike mosquitoes, they don’t warn you with a whine or even make themselves easy to see. You just start getting pin-pricks and then start itching.
But what exactly is a no see-um and what good are they? The biting midges we have here belong to the Genus Culicoides and they are Dipterans, like a house fly. However, there are many different species of Culicoides, with 47 species known to Florida alone. There are a 1,000 species in this genus worldwide. Some coastal counties of southeast Florida also have an additional genus of biting midges, Leptoconops, which occurs in the tropics and subtropics.
The mouthparts of midges have cutting teeth on long mandibles, and both males and females feed on nectar. However, the female’s mouthparts are also modified for sucking blood, which she needs to produce eggs. It is the female no see-um that bites or cuts your flesh and then sucks the plasma or blood at the wound site.
The female will seek out moist areas to lay her eggs. The eggs cannot stand drying out. Depending on the species, they may lay eggs in moist areas near ponds, ditches, rivers, rotting vegetation or manure piles on farms. With the tides constantly keeping salt marshes damp, the salt marsh habitat is a major producer of biting midges. Fortunately, the female no see-ums can range no more than a little over a mile from their breeding site and the males half that. Unfortunately, narrow coastal barrier islands and spits are usually well within that range.
No see-ums do not inhabit homes or live inside humans or other animals. Some species of biting midges are vectors for certain diseases in Central and South America, and are transmitters of bluetongue virus in the U.S. which affects sheep and cattle. Some horses have allergic reactions to the bites and can develop an allergic dermatitis. While the itching from a bite subsides fairly quickly in most people, others experience more severe reactions and sores at the site of the bite.
Large scale efforts to eradicate biting midges have proved impractical. Historical efforts to ditch and drain marshes were not only ineffective, but destroyed productive wetlands. Applications of insecticides are impractical for the vast areas needed to be treated, the cost of such efforts, as well as the ecological damage to other species. For most people, no see-ums are just a nuisance. Most insect repellants, especially those containing DEET, will work to keep no see-ums from ruining your backyard cook-out or camping trip.
These tiny flies serve an important role in the overall ecosystem in that they are in turn an abundant and important food source for birds, bats, spiders, other insects, and especially tree frogs. The more we protect the habitats of bats and birds, the fewer no see-ums we have. The loss of Culicoides midges would devastate other species that rely on them as food, and limit the species diversity that keeps our marshes healthy. A few bites are a small price to pay for the lush and productive marshes that help make our area such a worthwhile destination for fishing, scalloping and diving. I just wish the bats and birds would eat more of the little monsters.
Tom Baird has been a fisheries biologist, high school and community college teacher (oceanography and microbiology), director of a science and environmental center, teacher of science and principal in Pinellas County as well as an educational consultant. He retired from the Florida Department of Education and he and his wife divide their time between Tallahassee and Cape San Blas.