Insect eating root tips of leafless ghost orchid!

[mremensnyder]

So just a week ago I received my 2.5"-3" ghost orchid (Dendrophylax lindenii) from Orchids Limited. Knowing what a problem fauna of all sizes can be for small and delicate plants, I have kept it hanging over the inside edge of a 1 gallon Tupperware container with water in the bottom for humidity. This container is in a 4' x 3' x 3" aluminum cage (with aluminum screen sides) for protection. I bought 4 of these cages years ago just for protecting plants from squirrels and rabbits.

My ghost orchid has two roots which have light green actively growing tips and I noticed a round "divot" in one of the two roots tips last night. This evening I noticed the other tip has been eaten in the same fashion. I am horrified! I just got two other leafless species in the mail today (Microcoelia bulbocalcarata and Taeniophyllum pusillum) and I do not intend to see these three (expensive) orchids slowly eaten away to nothing! Is it a small snail or slug of some kind? What should I do about this?

[King_of_orchid_growing:)]

A slug would destroy what you've got in no time flat. It could be a tiny snail though…

However...

I think it's most likely fungus gnat larvae. Use a jeweler's loupe and look for a caterpillar-like looking insect with a translucent body, and a black head.

[mremensnyder]

Thank you for the reply.

I looked today and sure enough, a couple of the Microcoelia root tips were gone. This evening I gave the cage a thorough cleaning and removed some pots that still had media just laying around as well as some other potential pest harboring detritus that had built up in the outdoor situated cage for the last several years. I sprayed pesticide under where the cage was and put it back in place. For humidity, I put the plastic bottom of an orchidarium I had over a decade ago in the cage and filled with water. I poisoned the standing water, then put a plastic egg crate with the opened side facing up. After spraying the inside of the cage with insecticide, I hung my three orchids on the inside of the egg crate. I will spray pesticide in the cage weekly going forward.

This certainly seems like a stark and sterile habitat for the orchids, but whatever works! I hope this environment will kill flying pests and prevent snails and the like from getting to the orchids due to the water barrier.

[lepetitmartien]

Never underestimate the intelligence of hunger…

Could be snail/slug, there should be some goo at one place, showing their trail.

Could be cockroaches too…

To build up a defense without knowing first the offender is putting energy to waste…

[Leafmite]

Good luck! I had the same problem and it was these little, flat snails. They ate the root tips of my orchids and put holes in the leaves of my plants. I got rid of them by picking them off while they were in the house but I worry about new ones finding their way....

[tarev]

Must be slugs..did the same to my Oncidium Dancing Lady ate some roots tip and a spike

[lepetitmartien]

You can make a barrier on an enclosed volume by putting a copper ribbon around the opening. And be careful of what you are putting in.

Snails/slugs can be in any dark/wet area during the day. You can try to catch them with potato/carrot slices, if they find them gullible, it does not work with exotic gastropods seemingly…

You can put ferric phosphate around. If it's gastropods…

[mremensnyder]

I agree with everyone, it is frustrating. I do not see any slimy trails to hint at what's causing the damage. It just isn't practical for me to stake out for tiny insects in the middle of the night in my parents backyard

The best I can do at the moment is ensure a physical barrier with toxic (to insects) water. I am pretty sure the mounts that the 3 orchids are on are not themselves harboring the pests, but I plan to soak each (plant and all) in water for a couple hours this weekend, just in case. I removed all of the potential hiding places from the remainder of the cage and liberally applied insecticide spray as well. This weekend I intend to apply slug/snail bait too.

I am confident this approach, if maintained, will take care of the problem. I do not know for certain the exact culprit, but I will treat for each on the list of possibilities. That should cover it

[Leafmite]

I hope it works!
The little snails I had didn't seem to leave a trail that I could see. I think they were just too small. Well, it seems as if you are covering all the bases. Good luck!

[King_of_orchid_growing:)]

If it's fungus gnat larvae, they're easier to find than you think…

Just grab the plant and look with a jeweler's loupe. They don't travel far from where it is moist and cool, where things are moldy or rotten.

You can also grab a slice of potatoes, and place it near the orchid(s) at night, and see what gets on the potato.

Slugs are easy to trap with beer. A shallow pan of beer will net you some slugs for sure.