Starving mountain pine beetles in central British Columbia have moved into spruce trees as the supply of lodgepole pines disappears, scientists report.

Although spruce are generally not nutritionally or chemically suitable for the beetles to reproduce, they still do enough damage to kill the trees.

The mountain pine beetle has devastated forests across much of British Columbia.

Thus, while the loss of the spruce trees has left its mark on the landscape in the region from Kamloops to Prince George, the beetles aren't spreading any faster because of it.

However, some of the beetles have been able to reproduce in the spruce trees, insect ecologist Allan Carroll of the Canadian Forest Service told CBC News Thursday.

"Scientifically, we are watching it with a great deal of interest," said Carroll, adding that the scale is too small to cause major public concern.

Last year, more than 9.2 million hectares of B.C. and Alberta forest were in an advanced stage of attack from the tiny, but voracious beetles.

As they seek new food sources they are moving east. The worry is that the beetles will soon hit the mother lode of pine trees in the boreal forest.

If the beetles jump from the lodgepole pine to the boreal forest's jack pine, an infestation could wipe out billions of trees all the way to the East Coast.

Carroll said that the infestation is confirmed as far east as the Swan Hills area of Alberta — about 200 kilometres northwest of Edmonton — on the doorstep of the jack pine forest.

The extent of the spread of the beetles should become apparent in the next month as the infested trees start to die, he said.