When is black fly season in the 100 miles wilderness?

[The Kisco Kid]

I have heard early June, but also Father's Day to July 4th.

Any Mainers with local knowledge of the trail north of Monson?

[Lone Wolf]

i went SOBO one year in late june. no black flies but mosquitos were horrendous

[peakbagger]

Generally they are their worse between mothers days and fathers day (middle of May into middle of June). Its highly variable, depends on snow pack and when the thaw hits. As Lone Wolf commented, the mosquitoes move in when the black flies taper off. Given the warmer winters I expect they are coming out a bit earlier.

[Slo-go'en]

Black flies are around all summer, but typically peak some time in June. Exactly when is hard to say, it all depends on the weather. When the weather switches from cool and rainy to hot and muggy is when they spawn big time. This seems to be happening earlier every year. In general, you don't want to be in Maine, NH or VT until July. Black Flies spawn in shallow running water and like pine/spruce trees, so when you have this combination in an area or near a shelter, it can be bad.

[Lone Wolf]

just bring a head net, long sleeves, long pants and DEET

[TJ aka Teej]

I have heard early June, but also Father's Day to July 4th.
Any Mainers with local knowledge of the trail north of Monson?

I'm up between Caratunk and Katahdin quite a bit most years during blackfly season.
Few of the 40+ types bite, most just annoy you by hanging about in front of your face.
Bring a head net. Sleep in a tent. Take breaks in breezy spots.

[AllDownhillFromHere]

Black flies breed in running water; they generally simmer down after the first significant heatwave. Lone Wolf is spot on, it's the mosquitoes that get you. I spent hours resting in the Fort Relief privy simply because I couldn't go back out and face them.

[Ktaadn]

So when do most of the bugs go away for the year? September?

[Slo-go'en]

So when do most of the bugs go away for the year? September?

They don't really go away until the first killing frost in October, but by early summer the numbers are tolerable. Black flies are daytime bugs, mosquitos are night time bugs, with a little overlap in the evening.

Hiking when the black flies are thick, a cloud of them will follow you into camp. Immediately starting a small, smoky fire helps clear then out. This also helps to some extent with mosquitos. The only real solution is to get into your tent or bug bivy as soon as possible.

Some people don't react well to black fly bites and welt up big time. Most people develop an immunity after a dozen bites or so and aren't bothered by the bites anymore for the rest of the season. But they are still really annoying with 1000's of them swarming around your head, with them getting into your ears, up your nose, in your eyes and stuck in the back of your throat making you gag. The only way to avoid that is to hike with a head net, but that's really hot and suffocating. Forget about repellants like DEET, black flies aren't fazed by that in the least.

[peakbagger]

Black flies are trout food, they only breed in clear cool water. If you are coming to Maine it comes with the deal. Realistically mosquitoes are only real bad in June, from then on they may be around before and after dusk until September but they are rarely an issue after late July.