My orchids are being devoured by a plague of caterpillars...
Does anyone recommend a certain brand of insecticide for orchids (in spike). In the past I've used a systemic insecticide Imidacloprid, which worked well, but I know that's been banned. I've been using Safer brand insecticide (Potassium salts, fatty acids, sulfur compounds) but I'm convinced that it doesn't deter/kill anything...
For caterpillars particularly, Bacillus thuringiensis (BT), which also works on things like tomato hornworms, - it is a bacterium that specifically infects these larvae, and is harmless to humans and animals. They stop feeding and die. I don't think most of the pesticides do much against caterpillars, but this stuff does.
If you’re growing outside BT is also less likely to damage spider and wasp populations. These guys can do a number on caterpillars and moths when they’re well established in your garden.