A type of budworm is posing a serious threat to forests and livelihoods in the Cape Breton Highlands, government officials say.

Nova Scotia's Department of Natural Resources announced Tuesday that large areas of the island are infected by the blackheaded budworm.

The bug, similar to the spruce budworm that caused a devastating outbreak in the mid-1970s, has been found in 114,000 hectares of trees just below the Cape Breton Highlands National Park.

The blackheaded budworm.

"These are the same forests that have recovered from an outbreak of the spruce budworm more than 20 years ago," said Eric Georgeson, the province's insect expert.

Almost 40,000 hectares are already seriously affected, according to an insect egg survey.

Scientists don't yet know whether trees in the national park itself are infected because they haven't surveyed the area.

Provincial officials believes the budworm is in the first of a possible four-year cycle. It feeds on new foliage in balsam fir trees, and then moves on to the older trees once all the edible foliage from the younger trees has been destroyed.

Most of the trees showing signs of budworm damage are vigorously growing balsam firs standing 9 to 12 metres tall.

"A heavy infestation can completely defoliate trees, may reduce growth, and can cause widespread tree loss," Natural Resources warned in a news release.

The Highlands have regenerated since the spruce budworm outbreak thanks to extensive planting in the 1980s.