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## Biting Gnat Control

What are black flies?
Black flies are commonly called biting gnats. They are closely related to mosquitoes. Female black flies suck blood in order to develop eggs. Males do not bite but feed on plant nectars. Female black flies range in size from an eighth to a quarter of an inch.
The black fly bite...
The painful, itchy bite of the black fly is characterized by a reddened weal with a wound in the center. The wound is created by the female when she cuts a hole in the skin to suck the blood that seeps into it. In the process she injects anticoagulants, a pain killer (to remain stealthy!), and some toxins. The pain and swelling of the bite are due to an allergic reaction to these foreign proteins and a response to the toxins. Black flies do not transmit any diseases to humans in Minnesota.
Black Fly Life Cycle
Shortly after emergence from their larval breeding site, adult male and female black flies mate. The female then must locate a blood-meal to complete development of her eggs. Egg development is completed in 2-4 days. The female then locates a river or stream in which to lay them. Depending on the species, this will range from the tiniest spring to the Mississippi River. Female black flies generally ambush their victims from tree-top perches near the edge of an open area. They are active during the day with peak activity in the morning and early evening. Females live from one to three weeks, depending on the species and weather conditions. They survive best in cool, wet weather. Studies done by MMCD show that the majority of black flies in the region lay only one egg batch.

When the eggs hatch, the tiny larvae begin their life in the stream. They eat by filtering food from the running water with specially adapted mouth parts that resemble grass rakes. They grow to about 1/4 inch when fully developed. This takes from 10 days to several months, depending on the species and the water temperature. They then enter the pupal stage where transformation to the adult stage takes place. The 

## News!

North American Black Fly Association

The Eighth Annual Meeting of the North American Black Fly Association (NABFA) will take place on February 4-5, 2010 at the Archbold Biological Station in Lake Placid, Florida US.

Click here for meeting details

Click here for meeting registration form

RECENT MEETINGS The Seventh Annual Meeting of the North American Black Fly Association (NABFA)took place on February 4-6, 2009 at the Archbold Biological Station in Lake Placid, Florida US.

The Sixth annual meeting of the North American Black Fly Association, was held in Laughlin, Nevada, at the Riverside Hotel Casino and Resort, February 6-8, 2008. Meeting agenda and program 

## Metropolitan Mosquito Control District http://www.mmcd.org/gnat.html

1 of 2 5/13/2010 2:18 P Madult emerges from its pupal case by riding a bubble of air to the surface, much like what happens when you put a ball under water and let it go!
MMCD control technique
MMCD treats streams and rivers in the Twin Cities metropolitan area with a liquid formulation of Bti, a naturally occurring soil bacteria. This bacteria kills larval black flies while they are still in the water. MMCD operates under a special permit from the Minnesota Department of Natural Resources. Treatments begin after samples show high numbers of biting gnat larvae developing in rivers or streams. Rivers treated include the Mississippi, Minnesota, Rum, Crow and the South Fork Crow.
MMCD black fly links

Larval Control Adult Monitoring Non-target Monitoring FAQs Links 

## Metropolitan Mosquito Control District http://www.mmcd.org/gnat.html

2 of 2 5/13/2010 2:18 P M