This is not only desireable for comfort, but is also important to avoid vectors of disease, like Lyme Disease and West Nile Virus.  A recent article in The New York Times addressed this issue: "Simple Steps Can Keep Biting Pests at Bay" (Tuesday, August 7, 2001, section D8).  "In addition, avoid the outdoors at dawn and dusk.  And remember that the best protection against tick bite is a prompt shower and self -examination after being outdoors, especially in wooded areas.  This reminds me of the very low-tech and most effective method for reducing the spread of infection in hospitals, both by health professionals and by visitors:
WASH YOUR HANDS!

GS