Whitefly on mint
Without seeing the pest in question it’s difficult to comment if you have Whitefly or indeed Mint Aphid however the Pyrethrum based spray that Julian advised to use is what I use on these types of pests in Stephanie’s Kitchen Garden. If you follow his instructions and continue to spray to break the life cycle this should sort the problem out.
Marigolds or Basil is often used adjacent to tomatoes and other vegetables because of it’s strong smell or either the whitefly prefer the marigolds or basil to the tomatoes – it’s not a proven control, however I use marigolds and basil for this purpose, anything is worth a try!
Lynn Burton - Horticultural Advisor / Kitchen Gardener