A report from the Central 1 Credit Union predicts the mountain pine beetle's gluttonous binge of B.C.'s forests will cost 11,250 forestry jobs in the next two decades.

And because of the lack of alternative industries, the economic analysis said another 9,500 indirect jobs will be lost in the Interior.

It's estimated that by 2020 the beetle will have killed 67 per cent of the mature lodgepole pine in the province, with the greatest impact on communities that have less diversified economies, the report said.

It estimates that Prince George, Williams Lake and Kamloops will have to absorb about half of the total timber supply loss, but the impact would be limited in Prince George and Kamloops because of economic diversity.

"In the highly impacted areas at the heart of the outbreak, the current beetle infestation has run its course, but not without significant damage," the report said.

As of 2009 more than 70 per cent of the live mature pine in the timber supply areas of the Cariboo region, including Quesnel, 100 Mile House and Vanderhoof, were estimated to have been killed, the report said.

While the infestation is on the downward trend, the epidemic is still expected to spread southeast and northwest in the province.

It's clear the annual allowable cut will be significantly cut, the report said, and is expected to remain at very low levels for at least the next 25 to 30 years, before rising as young pine matures to timber that can be harvested.

And as jobs shift, the report said, so does the forestry-supported population, with a projected decline of 28,700 people from communities where as many as 11,500 homes will become vacant.

B.C.'s lumber industry has already been battered by a 77-per-cent drop in U.S. housing starts since 2005.

The report concludes that growth in alternative industries such as mining, natural gas, alternative energy industries and transport will play a major role in mitigating much of the job losses in areas that aren't completely dependent on timber.

"At the current time numerous mines are proposed in the Interior and Northwest, with estimated capital costs exceeding $8 billion," the report said.

"While the Mountain pine beetle will have far-reaching impacts on B.C.'s forestry industry and forestry-supported employment levels, alternative opportunities will be available to minimize the impact on local employment and population."