He avoided both during his first trek to the North Slope. Halfway through summer, he asked his colleagues how many times they were being bitten during an average day. About a dozen times, they answered. The only reason I stayed up there was that I don't react at all to mosquito bites,'' he said. These squat flies with large, rounded wings and a distinctive humpback shape tend to congregate in forested areas and along waterways.
Many people are allergic to their bite, which can itch for days, sometimes weeks.
Ed Holsten, an entomologist with the U.S. Forest Service in Anchorage, said he has received calls from doctors as far flung as Texas who have seen patients suffering from bites long after their vacation was over. Black flies are unusually sneaky and persistent. Unlike mosquitoes, they like to crawl around in search of the choicest bites. A couple of years ago, Jake Schlapfer and a colleague were traveling down the Unalakleet River about 400 miles northwest of Anchorage. An outdoor recreation planner for the federal Bureau of Land Management, Schlapfer checks on the condition of rivers and nearby recreational areas.