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Fungus Gnats

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Fungus gnats are very small flies (3mm) that look like tiny mosquitoes. They are grey or black, have very long legs and a pair of see thru wings. 

fungnatadult_1.gif funguasknat2_1.jpg
Adult Fungus Gnat (left)-Insect Control Branch, Winnepeg, Manitoba Canada, Fungas Gnat on a yellow sticky trap (right)-University of Florida

Description 
Larvae are extremely tiny and are very hard to see. They are whitish to greyish with black heads. Handpicking is a tough job.

fungusknat1_1.jpg fungusnat4_1.jpg
Larva (left), Eggs (right)-Minnesota Deptartment of Agriculture

fugnat3_1.gif
Lifecycle-Rutgers Cooperative Extension

Habitat and Lifecycle
They are found worldwide and they are mostly pests of your houseplants, potted plants outdoors, greenhouses & bedding plants. They love moist highly organic soils. Larvae live in the soil and adults live just above soil line. When watering you will know if you have them as they fly about madly. In the house they are found all year long and mostly in the fall outdoors.They have a continuous lifecycle completed in about 2 weeks so control is extremely hard.

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Damage-University of Florida

Diet and Damage
Larvae are more apt to damage the roots of your plants if they haven’t got enough moisture. They are found anywhere in moist, highly organic soils. They can cause major damage to small seedlings causing them to wilt and die from lack of roots. They can also spread disease.

Control
1) Dry Out Your Soil
Whenever possible let your soil dry out for a few days, the larvae will die from lack of moisture.
2) Bt & Bti
Follow directions on the label. Bt only works for a few days and then reapplication is needed.
3) Yellow Sticky Traps
Place sticky traps near the plants affected and then water the soil…..the adults will fly up and be trapped.
4) Quarantine New Plants
If you buy plants from a nursery you can cover it with a fine mesh for a few days to make sure that you haven’t bought a plant that has larvae.
5) Parasitic Wasps
There are many of these types that lay their eggs in the worm and this becomes food for the baby wasp.

Filed Under: Harmful Bugs

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Comments

  1. Cahri says

    August 28th, 2005 at 8:26 pm

    That would be the fly ‘poo’. It is fungus gnats, let the plant dry out after an application of soap and water. Just flush the plant outside with soap and water. This should kill the grubs so there will not be another generation. I would leave this plant outside as long as you can since the lifecycle of these guys is repeated approximately every 5 weeks.

    Reply
  2. tammy doane says

    August 28th, 2005 at 1:58 pm

    I have the little black dots on my bathroom walls. I have a large plant that I have now taken out side. In the pot there are white round things and worms, what is this?

    Reply
  3. Cahri says

    August 7th, 2005 at 10:38 am

    That is definately what you have. They probably were in the mulch you bought. Spray the mulch and all the plants with a mixture of 2tbs of dish soap in a spray bottle of water. Add a few drops of oil to help the mixture stick. You can also dilute rubbing alcohol with water. Mixture rate 10 to 1. They love humid, moist organic soils. These guys have also been known to bite.
    Regards
    Cahri

    Reply
  4. Linda Y. Bonow says

    August 7th, 2005 at 10:32 am

    I need more info I think this is the name of the pest clingling to my screens and house–When I sprayed the mulch or plants around the house they fly up and about they just cling to the house–until mid day then they swarm out again at dusk– I never haqd this so badly as this year

    My son bought opened bags of mulch to redo my garden plus we have had a lot of very humid weather could this be the reason—At first I thought they were mosquitos I have been searching for their common name and your description seems the best–I live in South Jersey–

    Can you give me nmore help???

    Reply

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