There are as many "cures" for sand flies as there are flies. The incidence of the critters is random throughout the year, and not everyone is bothered. Prevalent wisdom, including that of one the physcians in SP, indicates that perhaps double doses of Vitamin B Complex works pretty good. Take two tablets a day a week prior to your trip and also while there. Apparently gives your skin/blood a slight sulfur smell. Yummy. We're not bothered by them, but the vitamin B thing worked for our kids at Christmas.
On the other hand if you injest enough of those "nasty" blue things, you will NOT care the least about insects, or much else for that matter. (Or so I've been told)
[This message has been edited by CHOOCHOO (edited 03-25-2001).]