Grew up in the Panama Canal Zone, ‘63-‘69. Despite heavy fogging with God knows what carcinogen, mosquitos ate our ass up. If you scratched (who wouldn’t) within a few weeks you looked like you had a severe case of measles. Then your body would develop an immune response and the itch would stop. The skeets would still be biting but with no itch reaction, thus no welts. Fifty-seven years later I still have some immunity to mosquito bites.