sharing this/copy pasting something:

Note that organic is not always safe. For instance, a very effective organic pesticide is nicotiana, made from the tobacco plant. It’s all-natural but highly dangerous – you must wear gloves and a gas mask or it’s lethal! I’ve used it but there are easier and milder ways to deal with orchid pests.

The traditional fix for all these problems has been dish detergent. Not any more! It now contains antibacterial and grease-cutting chemicals that are dangerous to orchids. Ivory and Dawn are the mildest, but not as safe as pure castile soap such as Dr. Bonner’s. If you must use dish detergent be sure to highly dilute it: 1 teaspoon to 2 quarts. Place the solution in a spray bottle and spray both the plant and the soil. Use your fingers to gently rub off scales, webs, and honeydew. Wait a week and reapply.

These insects can also be eradicated on contact with a solution of 1 part alcohol and 1 part water applied with a q-tip.

Surrounding your orchid with nasturtiums and/or chrysanthemums will keep insects away, but not get rid of insects already on your plant.

Neem oil from the neem tree of asia is not harmful to plants or humans, biodegradable in 2 weeks, and also protects your orchid from fungal infection and root rot. Mix 1 oz of neem to one gallon of water and spray both plant and soil.

You can also purchase beneficial insects to control pests. Lady bugs eradicate aphids and mealy bugs. Praying mantises eat aphids and scale. Green lacewings eat mites and aphids. Beneficial insects can be ordered online or from your local garden center.

If you prefer a chemical, try an environmentally-friendly one such as pyrethrin-based insecticides. Pyrethrin is derived from the daisy family of plants, particularly the chrysanthemum. It decomposes within 1 to 5 days, and poses less harm to the environment than other chemicals if used properly. However, I would never use it indoors as it can be harmful to pets and sicken children, and recent studies suggest that it may be carcinogenic.

Many gardens have a healthy population of snails and slugs. They are beneficial for many plants, but not orchids. Install orchid protectors like copper strips to prevent them from climbing onto your orchids.