Ants: Don’t like Peppermint or Spearmint. I can personally testify to the Peppermint thing, which was the only way I was able to win the war on hordes of ants marching into my home one summer. I drew a line (literally) on the metal threshold of my sliding glass door, and it was the only thing able to convince the little critters to stay away from my kitchen thank-you-very-much!
Aphids: Don’t like Cedarwood, Hyssop, Peppermint, or Spearmint.
Beetles: Can’t stand Peppermint or Thyme
Caterpillars: Stay away from Spearmint or Peppermint.
Cutworms: Don’t like Thyme or Sage
Gnats: Don’t like Patchouly or Spearmint.
Lice: Scram when they smell Cedarwood, Peppermint, or Spearmint.
Mosquitoes: Don’t like Lavender, Lemongrass, or Idaho Tansy
Slugs: Ewww. Can’t stand Cedarwood, Hyssop, or Pine.
Snails: Heave-ho them nasty plant-chompers with Cederwood, Pine, or Patchouly
Ticks: Don’t like Lemongrass, Sage, or Thyme.
Weevils: Don’t hang out around Cedarwood, Patchouly, or Sandalwood.
These are all oils which some people have found helpful in relieving themselves of insect conventions. I have not personally tried all of them myself, so your mileage may vary. However, it is giving me ideas to go see what happens when I put a drop of Cedarwood on a snail or two. I know salt makes them explode or something (never did it myself). But I think my poor garden would thank me, regardless.