The following questions were
sent to the P&PDL diagnosticians
here at Purdue University:
Question 1: I have noticed little black flies around
my houseplants. What are they?
Question 2: How do I safely dispose of gnats that are
apparently living in the dirt of my house plants? I'm really
concerned about what type of agent I should use due to our family's
Question 3: I have browsed
your site trying to find out what my household pest is. I have
what looks to be "fruitflies" in
my houseplants, the only thing that I could find that came close
was "Fungus Gnats", is this commonly what I have? I
would have thought they were beneficial because I assume they
are thriving on dead plant material, but I have my doubts. Do
Fungus Gnats look like fruitflies?
Question 4: I was viewing your site and thought you might
be able to help me. My wife and I have about 10 plants in our
kitchen. We have recently had a problem with tiny flies which
look almost like fruit flies. They have invaded the plants and
are driving me crazy. I tried a chemical bug spray. That worked
for a while but they just came back, and the spray stunk up the
kitchen for a week. I also tried misting them with a soap and
water solution but they will not go away. I hate to throw all
of them out. Can you help. Any tips would be greatly appreciated.
Answer: It sounds like you are describing fungus gnats.
Fungus gnats are common pests in greenhouses and homes throughout
the U.S. Larvae of fungus gnats (maggots) are white with shiny
black heads and are approximately 1/4 inch in length. Adults
are black or brown in color, slender, and 1/8 inch in length.
They have one pair of delicate, clear wings and have long, slender
antennae. The adults are often confused with mosquitoes because
of their long, slender dangling legs. Females can lay up to 200
small whitish eggs in the soil. Upon hatching, larvae will begin
to feed immediately on the roots of plants. As soon as the larvae
are mature, they pupate in the soil. In about four to seven days,
the adults emerge and will live about one week. Larvae have the
ability to damage plants by feeding on roots and root hairs.
Seedlings and young plants are extremely vulnerable to this feeding.
The larvae also have the ability to bore into stems, interrupting
nutrient and water flow, which decreases the plant's health and
vigor. Adults and larvae are both capable of transmitting fungal
Proper sanitation and chemical applications are the most common
measures that can be taken to control fungus gnats. For additional
information on fungus gnat control, refer to publication E-111,
Fungus Gnats and Shore Flies (173K/PDF), which is available
at your local Cooperative Extension Service office.
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