A warmer than usual December last year means the blackflies that typically choke the air in some parts of Nova Scotia in the spring are conspicuously absent.

A patch of cold weather and snow last November was followed by a string of warm days heading into December.

"What happened is that the blackflies, which over-winter in streams as pupae, emerged," said Andrew Hebda, curator of zoology at Nova Scotia Museum of Natural History.

Blackfly season in December is virtually unheard of, but that's what happened in many areas of the province. And it means there are fewer pests left to pester this time of year, though they still persist in some local areas.

"The neat thing about blackflies is they only have one generation per year, that's called univoltine," said Hebda. "So once they've hatched, the females go out and have their blood meal and lay their eggs, that's it for the year."

The early season doesn't mean blackflies are in any danger for subsequent years.

They produce lots of copies of themselves when they mate, so there shouldn't be any shortage of them next season, even if that season comes in December again.

In contrast to blackflies, mosquitoes can have four or more generations of offspring in a year, so there should be no shortage of them, said Hebda.