growing outdoors and caterpillars
 

I moved many of my Phals outdoors for the summer. I live in northern Delaware and the temps and humidity in the summer have made them grow plenty of new roots. I have had a problem with caterpillars eating the leaves and some root tips. I have them sitting on the ground under a few bushes to keep them shaded.

What can I do to lessen the chance of getting eaten next year? I think most caterpillars in my area have morphed already as I do not see much evidence anymore.

Products containing BT (Bacillus thuringiensis) are good for controlling caterpillars. Nothing much else will - pesticides don't touch them. It is non-toxic to humans (works on tomato hornworms too...), prevents the caterpillars from being able to feed. Spinosad is a synthetic that was designed to work by similar mechanism, I have not found it to be as effective as BT, though. I also suggest getting the orchids a bit off the ground (I use bricks) to keep soil-dwelling beasties out of the pots. That won't help for the caterpillars, whose "parents" fly and can deposit eggs any place.

It also wouldn't hurt to spray your plants with Azamax, which is a concentrated form of azadirachtin, the active ingredient in neem oil. It avoids the potential issues of oils, and while you might still see a nibble of two, they will generally leave your plants alone.

With plants sitting on the ground, are you sure the damage is not from snails or slugs? (Have you seen caterpillars, or pellets of their waste, called "frass"?)

Thanks for the info so far.

Orchidwhisperer,
I believe it to be caterpillars as I have seen them on one that I brought in that was getting eaten pretty badly. I actually didn't see the caterpillar until the next morning. However, I do have a ton of slugs crawling around every night. Would the bricks help with that as Roberta suggested or should I figure out a way to hang them? Most of my Phals I acquired in the winter as rescues. I really didn't have much hope for them. I did water culture and 75% of them grew some roots, the others developed crown rot and were tossed. When I put them in sphag and placed outside, the others just took off growing roots. I really want to put them out next summer again, but have to figure out how to keep them from being eaten. I feel like they could have done so much better.

Maybe you could test carbaryl on 1 plant to start with. But you probably have to work out how the treatment schedule.

If slugs are an issue, bricks alone won't help much because they can crawl. You could put a cheap wire shelf on those bricks, to slow them down more. Hanging helps a lot... but I have even found slugs in hanging plants (do they fly???)... possibly climb down the hangers. But hanging will certainly keep most of the slugs at bay. And then watch for the occasional flying one...;)

If pigs can fly, then there's no reason that slugs can't.

More separation from the ground is helpful. There are probably many non-chemical deterrents you can try. However, once they find their way into a pot, you will likely need some sort of chemical to kill them.

I use metaldehyde bait (with precautions to keep away from our dog). There are many alternatives. Whatever chemical you choose, be sure that it says on the label that it kills slugs and snails (or that the package is labeled to indicate the product is a molliscicide).

I found a snail the size of my thumb nail on one of my walkerianas hanging about 9’ off the ground. I am at a loss and almost felt bad for killing it, he must have worked hard to get up there, lol.

I have been using a combination of snail and slug traps (the good ol cheap beer in a pie tin trick) and I put copper netting around the legs of my benches and shade house. It’s not perfect but it has helped. You could always try a combo of both.

I had a huge caterpillar problem this year for the first time when something hatched on the balcony above my shade house. Someone recommended a spray of some hot pepper mix and that helped a lot. I just boiled some little hot peppers and a spoon full of chili powder in water, strained it, and put that in a spray bottle. Didn’t eradicate all of them, but it helped and it didn’t harm my outdoor lizard buddies. I also used Rose and Flower Insect Killer sparingly on a few of my orchids that have small bracts or tight growing sheaths that the caterpillars would hide in and eat their way out. That killed off some bloom spikes (*sigh...) but it saved the orchids from being eaten.