| I'd have to be sure as to what they are.
There are scores of types of insect larvae that feed in decaying plant material and soil: they eat other insects, plant matter, bacteria, and fungi for example. Only if I knew what the insects were in the original thread, would I be able to say whether or not they damage roots.
Insects that live on dead plant matter make available nutriments that are in turn used by the plants themselves. This is a natural way of recycling materials and to me it is not a good idea to interfere, unless I am certain that what I am doing is not harmful. Man has a very poor record when it comes to interfering with age-old environmental processes.
Killing the insects has only short-term effects in any case. Gnats are mobile and will recolonise the growing medium unless the plants are isolated in sterile conditions.
Les |