HELENA, Mont. (AP) _ Boys who beat the heat in mini-skirts last month to protest a ban on wearing shorts to school have been rewarded with a change in the dress code.

But they also have seen a change in the weather.

About 30 Helena High School boys challenged the ban in April by donning skirts. On Tuesday, the school board voted to allow students to wear shorts, subject to the ''sensible discretion'' provision of the dress code.

The change took effect immediately, but so did a cold front, and only a few pairs of shorts were seen in the halls.

---

OSHKOSH, Wis. (AP) - The annual invasion of the May lakefly has this town buzzing with excitement.

In most places, the winged water-breeder is unwelcome, but on the shore of Lake Winnebago residents are gearing up for Sunday's second annual Lakefly Festival, which honors the pest as its mascot.

''I guess it's because everybody hates them so much,'' says Lakeflies Unlimited spokesman Ronald Schmitz.

Mashed lakeflies smear windshields and clog screens, but the 700-member club touts the virtues of its ubiquitous mascot on bumper stickers, T-shirts, mugs, posters and in its newsletter, the Flypaper.

The club's tongue-in-cheek proposals include:

- Relocating the city five miles inland because too many vehicles are striking lakeflies.

- Imposing restrictions on Japanese imports of imitation lakeflies.

- A U.S. Food and Drug Administration prohibition against house paint in which lakeflies get stuck.

- Putting lebands on 200,000 lakeflies so the state Department of Natural Resources can monitor their migration habits.

---

INTERNATIONAL FALLS, Minn. (AP) - This city on the Canadian border is so cold it has been dubbed the ''icebox of the nation,'' so civic officials say they might as well advertise it with a 22-foot thermometer.

City Council President Paul McLaughlin called the thermometer ''one more tool in the arsenal to market our city.''

The council voted 6-1 Monday to erect the thermometer, which will receive its temperature through a telephone hookup.

The $18,000 instrument will help maintain the city's reputation as the capital of cold, said resident Fred Boeckh.

''That's what we have to preserve,'' he said.