We've all seen the sensational headlines: according to the U.S. Forest Service, bark beetles, spurred on by the drought, have killed 25 million trees in California's forests this year, greatly increasing the spread and intensity of recent fires.

What we haven't seen is a critical assessment of these claims. Are bark beetles really increasing fire intensity? Are they really threatening the ecological health of our forests?

Many Californians, unfortunately, are content to avoid these questions. That number includes some state and federal legislators and their timber industry campaign contributors, who are taking advantage of public fear and misunderstanding of the ecological role of beetles to push for a huge increase in logging and clearcutting in California's forests.

Republican state legislators are urging Governor Jerry Brown to declare a state of emergency, freeing up millions of dollars from the state treasury to subsidize a massive commercial logging program that would cut down and remove dead trees statewide. In Washington D.C., House Republicans passed a bill, H.R. 2647, that would suspend most federal environmental laws to facilitate a huge increase in commercial logging of live and dead trees on our National Forest lands, ostensibly to save our forests from bark beetles and fire. The bill is now pending in the U.S. Senate, and Republicans and the logging industry are now attempting to persuade some Democrats, like Senator Dianne Feinstein, to support some version of the logging bill.

But the public is being profoundly misled on these issues. First, trees killed by bark beetles do not increase fire intensity and spread. Numerous scientific studies have been published on this issue, and they consistently reach this conclusion. The most recent and most comprehensive of these, published this year in the Proceedings of the National Academy of Sciences, investigated whether recent tree mortality from bark beetles increased fire spread, studying forests across the western U.S., including forests throughout California. Lead author Sarah Hart and her co-authors concluded that "the annual area burned in the western United States has not increased in direct response to bark beetle activity."

Other studies have investigated whether forests with higher numbers of dead trees from bark beetles burn more intensely, and over and over again they have found no such increase in fire activity. A 2009 paper by Monica Bond et al, which I co-authored, looked at the same question in mixed-conifer forests in the San Bernardino National Forest in southern California. Again, the forests with the highest levels of snags from bark beetles did not burn more intensely.

In still another paper published in 2011, Martin Simard and his colleagues studied both recent and older tree mortality from bark beetles, and found that neither increased the probability of crown fire (high-intensity fire), and in fact forests with higher levels of dead trees, known as "snags", often burned at lower intensities. Research by NASA, using satellite imagery, also suggests that forests with higher levels of snags from beetles tend to burn at lower intensities. Numerous other similar studies are summarized in a recent book I co-edited with Dominick DellaSala, "The Ecological Importance of Mixed-Severity Fires: Nature's Phoenix."

In short, this issue has been studied very extensively, and the overwhelming weight of scientific evidence from actual field research concludes that bark beetles do not seem to increase fire spread and intensity. Like many things in the field of forest and fire ecology, this may seem counterintuitive at first. But it makes sense upon deeper examination, and a number of explanations have been offered, such as the tendency of volatile oils to dissipate in the needles of conifers after trees die, and the fact that flames don't move as easily through the forest canopy once needles on dead trees begin to fall to the ground.

Rather than pests, both the bark beetle and wood-boring beetle species at issue are native species that fill essential roles in native forests. They evolved in these forests over many millennia; in many ways, they're a cornerstone of the biodiversity in forest ecosystems in California and the western U.S.

Periods of drought are natural in the western U.S., and most dead trees result from occasional pulses of drought and fire. These native beetle species require recently dead trees to survive, since their larvae depend upon the unique microhabitat and food conditions found under the bark of recent snags. Woodpeckers depend upon these beetle larvae for their food, and the woodpeckers need snags, which are softer than live trees, so they can excavate nest cavities to raise their chicks.