Slugs can live for around 2 years, and start life as an egg. These eggs are laid when the soil conditions are moist and can remain dormant until the conditions are right for them to hatch. Slugs are hermaphrodites which means that they have male and female reproductive organs.
Slugs are moisture lovers and thrive in damp media and will have great fun munching the orchids roots. If left to their own devices, they could prove fatal to your orchid. For those of you growing orchids in plastic pots, you should be able to see the condition of the plant’s root system. The condition of the ends of the roots can be indicator of whether slugs are in the media.
If you spot slugs in the media, there are a few things that you can do to help reduce their numbers. A key factor is vigilance. If you spend time checking your orchids regularly, you will notice changes and be able to adapt your care in good time. The same goes for pests; the earlier you notice a problem, the earlier you can start to treat it. If you spot any pests on your orchids, which grow next to other orchids, you will need to move them to prevent the critters from spreading.
I am aware that some people do not like to use chemicals or substances that kill little critters. You can try placing a slice of apple on the surface of the media before you go to bed, and then in the morning, turn the slice over and see if any slugs are there. All you need to do then is discard the apple, and replace as necessary until no more slugs appear. Be warned though, if the slugs have laid eggs, you may be doing this for some time. You could also remove the slugs manually and dispose of them as you see fit.
You could also unpot your orchid, ditch the media and spray the roots with hydrogen peroxide 3%. This helps to kill off any slugs that remain after the media is removed, and helps prevent the eggs from hatching. Leave the hydrogen peroxide to fizz away until you can no longer see or hear it. You can then repot your orchid in fresh media. Keep it in isolation for a few weeks and check for any further appearances. You can also soak the pot in hydrogen peroxide, but I find it more economical to unpot the orchid first.
You will need to keep an eye on your affected orchids for at least 4 weeks. Once the slugs have been removed completely, then you can place the orchid back in its original location in your home.
I hope this was helpful. If you have any questions, please feel free to leave me a comment.