Tool
Maine Black Fly Season
Roughly Mother’s Day to the Fourth of July, and worse the further north and higher you go. This is when each region is usually in it, and where to go instead.
Where the season is today
No region is inside its typical window today.
| Region | Typical window | Today | Reports |
|---|---|---|---|
| Aroostook and the far northCaribou, Presque Isle, Houlton | May 20 to July 10 | Past | none |
| North Woods, Moosehead and KatahdinGreenville, Millinocket | May 15 to July 5 | Past | none |
| Western mountainsRangeley, Bethel | May 10 to June 30 | Past | none |
| Kennebec Valley and inland MaineAugusta, Waterville, Bangor | May 10 to June 25 | Past | none |
| Downeast and AcadiaBar Harbor, Lubec, Eastport | May 15 to June 25 | Past | none |
| MidcoastCamden, Rockland, Boothbay Harbor | May 15 to June 20 | Past | none |
| Southern coast and PortlandPortland, Ogunquit, Kennebunkport | May 20 to June 15 | Past | none |
- Aroostook and the far north: First to turn and last to be free of flies. Both run about two weeks behind the coast in spring and two weeks ahead of it in autumn.
- North Woods, Moosehead and Katahdin: The classic peak-foliage destination, and the worst place in the state to camp in the first half of June.
- Western mountains: Elevation does the work here. A summit can be past peak while the valley below it is still green.
- Kennebec Valley and inland Maine: The middle of the state in both senses. Reliable mid-October colour without the mountain crowds.
- Downeast and Acadia: Acadia peaks noticeably later than the mountains, which is why the park is busy well into October.
- Midcoast: The sea holds the temperature up, so colour arrives late and hangs on.
- Southern coast and Portland: Last to turn, and the mildest fly season in the state. A sea breeze keeps the worst of them off the beaches.
Where these dates come from
The windows are long-run typical timing, not a forecast for this year. They move with latitude and elevation, which is why the north and the mountains lead and the southern coast trails by a fortnight.
No field reports have been approved yet, so nothing on this page is a live reading. When observations start arriving they will appear in the reports column, dated and credited, and they will sit beside the typical window rather than replacing it.
Any given year can run one to two weeks either side of these dates. A warm, wet autumn delays colour and dulls it; a cold spring pushes the flies later and compresses them.
The season, region by region
One shared axis, so the stagger is visible. It starts inland, in the western mountains and the Kennebec valley, around the tenth of May. It finishes first on the southern coast in the middle of June and last in Aroostook in the second week of July — nearly four weeks between the two, and the reason a June trip is a different proposition depending which way you drive.
Common questions
When is black fly season in Maine?
Roughly Mother's Day to the Fourth of July, worst from the middle of May through the middle of June. It starts earlier inland and in the south, and runs latest in the north and at altitude.
How bad is it really?
Bad enough to change plans in the North Woods in early June. They bite in daylight, they are worst near running water on still, humid days, and a head net is normal equipment rather than an overreaction.
Where can I escape them?
The open coast. A steady sea breeze keeps them down, so the southern beaches and the exposed headlands are the mildest places in the state during the worst weeks.
When do they stop?
The first generation fades as the streams warm and slow. By mid-July the flies are largely done and the mosquitoes have taken over, which is a different problem with the same solution.
