I've been wondering what's been going on recently: something's been wiping out my seedlings. I was starting to think that that my temperatures were all wrong or that I've suddenly lost all ability to grow Neps... until I found some of these little b******s.
On larger plants, they just cause leaf deformation, but on delicate seedlings, they seem to turn the leaves manky brown- until the seedling dies.
Larger plants seem to be cured by a spray with Provado (thiacloprid) without any ill effects, but I wonder whether using the insecticide is as damaging as the bugs themselves? I've found splashing some Provado vine weevil killer (thiacloprid again) into the soil prevents sciarids, so presumably it's safe.
There's no choice, I'm going to have to try it!