The hiccup of living in a climate like Newfoundland's is while we wait for winter to merge into spring and summer, we too accept the company of insects. Most simply mind their own business but the Black Fly needs your blood. :) Blackflies have begun to emerge in Newfoundland, though they were not-so-bad this past weekend. Temperature plays a role in hatching so numbers varied across the province. June tends to be a very difficult month for blackflies. Many campers/hikers question their choices around that time. I have been in the deep woods in June when they are simply a cloud - on every skin surface and in my mouth. Not fun. The Lure of the Labrador Wild vividly described just how bad blackflies can get.
You'll notice in Newfoundland that blackflies are around from spring through to early fall. They vary in size and aggressiveness. This is because we have about 12 different blackfly species emerging at differing times. There is a die-off during the hot days of July, making July to August tolerable days in the woods. Blackflies are small, 1-5 mm long. Both males and females use nectar for energy. The males do not bite. Females have biting mouth parts made for cutting skin and they use your blood for egg development.
Staying near the ocean - with open spaces and winds - is probably best if you do not wish to tolerate blackflies. Some believe that light clothing and few scented products reduce contact...but, they seem to like some people more than others! Bug lotions are effective to varying degrees. Some people develop allergic reactions to fly bites.
Enjoy the great outdoors!