Help! Sciarid Fly Larvae!

[Minamoo]

Help! I discovered these larvae in 3 of my sqaush seed pots where the seeds had failed to germinate. they were in a greenhouse FULL of seedlings and I'm panicking that they're all going to be nibbled away and die. What can I do to kill them off? I really can't afford to lose all my seedlings!

[Two_Sheds]

You need to water a bit less

[Minamoo]

You need to water a bit less

That's how I stop it from happening again. My googlefu is weak, but that much I did manage to figure out. But what do I do now in case the rest of them are infected as well? Some internet pages recommend wasihng all the soil off the plants and repotting with fresh compost. Which is easy enough if you've only got a few plants to worry about. But a right bugger if you've got well over 100 plants all in one spot!

[Two_Sheds]

My googlefu is weak, but that much I did manage to figure out

OK then, I'm off to bedski anyways

[Minamoo]

OK then, I'm off to bedski anyways

I didnt mean it badly! Please don't be upset! All I've managed to find out thus far is that it happens when you water too much and the flies lay their eggs in the damp compost, but I haven't been able to find out how to get rid of it once it's there. I value your opinion greatly. if this wasn't the case I wouldn't have bothered asking for help. So please dint be upset.

[Lotsaveg]

Check out a new biocontrol called Mighty Mite. Harrod Horticultural sell it and it's an aggressive predator of sciarid larvae.

Mighty Mite from Allotment Growing

[Two_Sheds]

I didnt mean it badly! Please don't be upset!

OK, I'm not upset now

Let the compost dry out a bit, and water from the bottom only, for a few mins. This is how I do it: YouTube - how to water seedlings

The fly will diminish greatly. If you have clouds of the adult flies, put some kind of sticky trap up above them. I've found a small amount of almond oil attracts them, they stick in it and die. Other oils may work too, as may the old fashioned sticky fly paper. Vacuuming with a small attachment?

The most important thing is getting that watering sorted. Your squash seeds probably rotted, esp if the soil was cold (I haven't sown mine yet). The flies (fungus gnats) didn't eat them. Good luck x

[ginger ninger]

I had an infestation in my cucumbers last year in the green house. I ended up digging my plants up and throwing away the top 2in of compost. I've been removing the larvae from the compost my red current bush is planted in. There mainly down the side of the pot, so there easy enough to spot. Nasty little things they are, have a read at this it might help. There's a link on there to where you can buy nematodes from and photos to help you identify the good guys as well.

[buzzingtalk]

i had them last year and they nearly ruined my adult chilli plants - i got rid of them by:

watering from below like 2sheds says
putting a layer 1inch thick of horticultural sand on top of older plants which don't need potting on for a while (such as larger houseplants) this stops the females burrowing into the soil to lay eggs and keeps the top too dry for them
put up some sticky traps, this worked for catching a few adults. i also found they love to 'swim' so left out saucers/bowls full of water with something sweet in it (oil/honey etc) and caught more of them, again this works well on adults
i bought some nilnat which i apply once a week when infested this helps to break the cycle and kills off any eggs/larvae.

[buzzingtalk]

the life cycle is about 3 weeks iirc so you need to be quite vigilant to remove an infestation but once you've broke the cycle it is much more easy to manage

[Minamoo]

Right. So today is looking like it's going to be a nice sunny day. I shall repot the pepper seedlings as I have seriously overwatered them and leave the greenhouse door open so everything inside dries out. All I've ever grown before is tomatoes. And they seem to need a lot more water than the peppers. But when the toms needed watering, I just watered the peppers too. Now they have algae on top. :S I shall separate the peppers from the toms so when I water them this doesn't happen and only water them by putting water in their trays. I will also get hubby to buy sticky traps during his lunch break. Thing is, I haven't really seen any little flies in the greenhouses other than one day last week when the greenhouse was full of all sorts of insects from large normal flies to bees. But it can't hurt to be over prepared just in case the adults reappear!

The predatory mites look like a good idea too but it says that the soil needs to be above 12C. My plants are all in greenhouses outside and I suspect that the night time temps are still dropping kind of low. Would this kill the mites?

thanks for all the advice everyone! At least now I am no longer panicking.