Caterpillars hatched

[Anniemike]

New orchid board member here and I am glad I signed up because this morning while watering my orchids I noticed small white caterpillars in the saucer of my Cymbidium orchid. I bought the cymbidium orchid a few months ago from a local nursery. Usually, I will repot orchids once I get them, but I didn't with this one. I dumped out the medium and found more caterpillars plump and fully formed as well as very skinny long worm like caterpillars (must the growth stage). Does anyone know what kind of caterpillar this is and how to treat it? I am going to repot the cymbidium in new medium. I must have caught it early because I didn't see any damage to the roots. Can I spray alcohol on the roots to kill any eggs? Or what should I use? Any help is greatly appreciated. Fingers crossed those litter buggers didn't crawl out and go into any of my other orchid pots. I've attached a photo. Thank you!

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Are they crawling as fast as caterpillars? They look more like mealy bugs to me.

[Roberta]

For killing larvae in general, BT (bacillus thuringiensis) is the thing to use. Harmless to humans, pets, and mature insects, it causes larvae to stop feeding, and die. (whether caterpillars or the larvae of other insects) I'd suggest getting some BT concentrate (available at nurseries and big-box stores), dilute according to directions, and give a good drench with it. (Used for tomato hornworms and other "crop" pests, so easy to find)

[Anniemike]

They are definitely caterpillars. I made a video but not sure if I can post videos to this forum?

[Roberta]

BT. Nothing else kills them with any effectiveness, BT is quite thorough. And totally safe. (It's approved for organic gardening) Something like this: https://www.amazon.com/Monterey-7045...00ANT611U?th=1 or https://www.homedepot.com/p/Southern...0028/100599150

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Have any Cymbidium growers seen caterpillars like this before? I haven't. I wonder whether they're eating living plant material or old dead organic matter.

I would immediately soak the root ball in a bucket of water with a few drops of dish detergent, just deep enough to cover the plant and pseudobulbs, for 4-6 hours. This should kill all the bugs. A few may come to the surface where you can pick them off.

[Anniemike]

Good idea. I removed all the medium. Sprayed it with water and then completely saturated it with hydrogen peroxide. I repotted it in a clear pot so I can monitor it. Fingers crossed.

[Roberta]

Originally Posted by Anniemike

Good idea. I removed all the medium. Sprayed it with water and then completely saturated it with hydrogen peroxide. I repotted it in a clear pot so I can monitor it. Fingers crossed.

Yikes. Rinse well and repeat... peroxide is deadly to roots, it destroys the little hairs that do the work. If you rinse it out quickly you may reduce the damage. The solution to pollution is dilution. But peroxide does its damage fast. If you didn't pick this message up and do it right away, rinsing may not help much... peroxide breaks down fast in the presence of organic material - it does its munching and it's done. In that case, just hope that the roots aren't too damage... Cymbidiums are tough, and this time of year they'll be putting out new roots soon.

[My Green Pets]

I've never seen caterpillars in damp medium, but millipedes on the other hand are very common. I think they're millipedes. I don't think they are particularly harmful, but dryer conditions will also reduce their numbers, in addition to the other suggestions here.

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They do look like millipedes, but I've never seen white millipedes.