Q.killing off whitefly eggs and other bacteria that may be left behind in the soil last fall
I had whiteflies in my garden last year for the first time ever. Not sure where they came from but I want to treat my garden soil before I plant this year to get rid of any eggs or other bacteria left behind. I was planning to treat it with hydrogen peroxide but was not sure how early I should apply this treatment. Is this something you would recommend, and when should the treatment be applied (how long before I plant my new garden)?

Certified GKH Gardening Expert
Here are two articles that should be helpful. The one on houseplants includes the garden, too. Whiteflies lay eggs on plants so they won't be in the soil. If you removed all your plants from last year, you should be good, 'til they invade your yard again. The eggs and pupa are resistant to insecticides, so control is difficult. There are some suggestions below, plus how to use hydrogen peroxide in the garden.
https://www.gardeningknowhow.com/plant-problems/pests/insects/control-whiteflies-houseplants.htm