Fungus gnats are often mistaken for

fruit flies, as their adult form looks very

similar to a fruit fly. Small and winged,

you’ll notice them when 

you shake or move your plant, as they

will fly up from the soil. These adults

are not harmful to your plant (but they

are annoying). Their larvae, however, 

live in the first two inches of soil

where it feeds mainly on dead or

decaying organic matter, although

some species can feed 

on root hairs and living tender roots.

 

In small numbers, the larvae also

shouldn’t damage your plant,

but as their numbers increase

they can cause root damage

and contribute to plant decline. 

They can also be more damaging to

cuttings and seedlings than to

established plants. They prefer moist soil,

so their presence can also be 

an indicator that your plants may be

staying too moist and you should check

the roots for any root rot they may

be feeding on.