Help identifying an orchid pest, please :)

[bethmarie]

I just unpotted a sickly cattleya hybrid to check the roots. In the lava rock medium, I spotted scores of fast moving, tiny maggot like worms disappearing into the holes in the lava. Ugghh. Really, really ugghh. Lots of dead roots on the plant, new growths were turning black, but not mushy, and dying.
I looked up thrips, and it doesn't seem like a match. Some kind of fly larvae maybe, but what I read about those didn't exactly match either.
Not sure if the dead roots and blackened growths are caused by the pests or something else.

Right now I just want to know what those repulsive, fast little worms were and how to make sure they are all dead, dead, dead.

[silken]

They could be fungus gnat larvae. You would likely have lots of fungus gnats hovering around if they are. Do you have a picture?

[WhiteRabbit]

I agree that it's likely they are gnat larvae. A soak in some (dish) soapy water should kill them. Letting media dry, or nearly so, should help keep gnats at bay.

[bethmarie]

No gnats at all. Sometimes see them around the sphagnum grown plants in the summer, but I've got nary a gnat right now.

The medium was lava rock, and watering was spaced 8-10 days, so I'm pretty sure it wasn't staying too wet.

---------- Post added at 09:10 PM ---------- Previous post was at 09:07 PM ----------

I don't have a picture. I was pretty repulsed- there were many of them, all speeding into holes in the lava rock.
The lava rock is zip bagged and in the outside trash now. I don't usually get grossed out-- snakes are fine with me, spiders are my friends, but swarms of maggoty things---yecch.

[This Side of Paradise]

Springtails?

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[katrina]

I would've guessed fungus gnat larva too but if not that, could they be centipede larva? You know, the ugly little centipedes we see in houseplants from time to time.

I don't know what their larva look like but maybe someone else does. I hate the adults! Even though I know they can be beneficial (eating other bugs and not harming plants)...I do my best to eradicate them because they creep me out.

[Leafmite]

Do you add extra calcium for the Cattleya or is the black some sort of fungus attack (or do you think it is caused by the bugs?). I ask because I once lost quite a few Cattleya and other orchids to Calcium deficiency. :|

As for the critters, you can always soak (in water with bleach), then bake the lava rock and reuse it. Part of the beauty of the stuff is its ability to be recycled.

I would guess it is fungus gnat larva. If there are decaying roots, they would find that to be a good source of food. If the roots are decaying, it is likely that, somehow, there are pockets in the medium that are not completely drying and providing a perfect home. Just a guess.

In addition to the lava rock and LECA, I use basket pots or Vanda baskets with my Cattleyas. Yet, still, even under the lights, when my orchids seem a little too dry, I still have a few pill bugs and fungus gnats (as evidenced by the butterwort). How? I have no idea. Somehow, they find the small areas that do not quite dry out.

[bethmarie]

Thanks for the help and feedback. I decided to man up, retrieve the lava rock from the trash and take pics. Figured that was the only way to really know.

Let me know what you think. I'll be searching for this nasty creature online in the meantime.

I don't add extra calcium, but my fertilizer is supposed to cover that. Maybe it's not? Don't think it's fungal, but not sure.

[Leafmite]

Thrips?

https://en.wikipedia.org/wiki/Thrips

I don't really know but hopefully, the picture will help someone identify them. I am not very fond of bugs in my plants, either. I have a few plants that breed fungus gnats and that led to buying a butterwort and a few more CP's.

---------- Post added at 11:52 AM ---------- Previous post was at 11:39 AM ----------

Springtails?

Home, Yard & Garden Newsletter at the University of Illinois

[bethmarie]

I looked at thrips and springtails and neither looks to me like the wormy things that were in my plant.
Did either look like a match to you?