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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

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adult 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

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