Subject: Whats this little bug?
Location: 95762 CA, US
January 13, 2014 11:06 pm
Mid January in Northern California near Sacramento. These little bugs have been bugging my plants in an aquaponics system in a hoop house. They also seem to leave webs of some kind behind. Any help would be greatly appreciated! thanks
Signature: Chris Haislet

Drain Fly

Drain Fly

Hi Chris,
This appears to be a Drain Fly or Bathroom Fly in the genus
Clogmia in the Moth Fly family Psychodinae.  We typically get identification requests regarding Drain Flies from homemakers who are perplexed by their appearance in bathrooms and kitchens.  In the home, the larvae live in the sludge that collects in drains and pipes.  According to BugGuide:  “Larvae feed on algae, fungi and bacteria in sewage and organic sludge; adults feed in polluted water and on flower nectar.”  We don’t believe they have any interest in your plants, but rather in the hydroponic system itself which may need some cleaning and maintenance.  We are not convinced the webs you mentioned are related to the Drain Flies.  BugGuide also notes:  “In the home, females lay irregular masses of 30-200 eggs in the organic gelatinous film lining drains, particularly in bathtubs and showers; eggs hatch 32-48 hours after being laid, when ambient temperatures are 70ºF (about 20ºC), and larvae pupate 9-15 days later; pupa stage lasts 20-40 hours; development time from egg to adult is 7-28 days, depending on temperature and food availability; adults live for about two weeks” and “Larvae play an important role in purifying sewage in industrial sewage treatment plants. Adults are very weak fliers, covering only a few feet at a time in short erratic flights.”

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Location: Sacramento, California

One Response to Drain Flies bug hydroponic gardener

  1. Brian says:

    This is a little late for this poster, but for those who, like me, have/had this problem in hydroponics, I have a solution: chlorine. This only works for those using synthetic fertilizers, as it will sanitize your system and will interfere with microbial breakdown required to make organic fertilizers function. So, unfortunately it may be illadvised to attempt this an aquatic system. With that said, a chlorine level of 0.5-1.5 ppm will stop them within a system. This works by eliminating the bio-film that tends to build up within most hydroponic setups. The use of chlorine may be continued after the pest is gone, as a preventative measure. It is important not to exceed 1.5 ppm as anything higher than 2ppm may also kill your plants. Also, the initial dosage should be monitored as level will drop as it dose its job. All future doses will be more long lasting. I hope this helps someone.

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