how do i get rid of fungus gnats and thrips on my poinsettia with out using pesticides?

Answer 1

Fungus gnats is a no brainer........pour soapy water through the soil........wait a bit-up to about 15 minutes.......then rinse through.

Thrips are another matter. Here's a web piece:
"Thrips Control: Remove weeds and grass from around garden areas to eliminate alternate hosts. Yellow sticky traps are helpful for monitoring adult populations. If found, use the Bug Blaster or hose off plants with a strong stream of water to reduce pest numbers. Release commercially available beneficial insects, such as Minute Pirate Bugs, Thrips Predators, ladybugs and lacewing, to attack and destroy all stages of thrips. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap, neem oil, and botanical insecticides can be used to spot treat heavily infested areas. Clean up crop debris, especially onion leaves after harvest.

Tip: Insecticidal soap, neem oil, and botanical insecticides are contact insecticides. For effective control, it is necessary to provide thorough coverage, especially inside the plant base of the leaves where the majority of pests are located."

Answer 2

Take a spray bottle with water and add a little dish soap and spray it on your plants. It has always worked for my regular house plants.