Now that pollination season has begun in earnest, I've been thinking more and more about bees.

Will we have enough this year -- and in years to come -- for our agricultural crops? Will I have enough in my own garden?

Probably no one would have given this a moment's thought before 2006, when Pennsylvania beekeeper David Hackenberg noticed something amiss. Hackenberg manages bees, trucking them from Florida to Maine to pollinate whatever needs it, according to the season.

That October, he had trucked them to Florida to pollinate orange blossoms. By November, some hives were empty; others had just sickly remains.

That was just the beginning.

Entomologists far and wide -- but Penn State was a nexus -- began to work on the problem, which came to be known as Colony Collapse Disorder.

Increasingly, evidence is pointing to a particular group of pesticides, neonicotinoids.

In a very nice New Yorker piece recently, Elizabeth Kolbert describes three studies that link the substances to the bee declines.

"As it happens, the studies are appearing just as Silent Spring, Rachel Carson's seminal study of the effect of pesticides on wildlife, is about to turn fifty," she writes. "It's hard to avoid the sense that we have all been here before, and that lessons were incompletely learned the first time around.

In another study published in Science Daily in March, researchers looked at corn-planting technology and concluded that the pneumatic drilling machines used to plant corn treated with neonicotinoid was expelling bursts of air containing high amounts of the insecticide. Honeybees that flew through the emission cloud died.

Today, the Pesticide Action Network released a report, Pesticides and Honeybees: State of the Science, that it says documents evidence that pesticides are a key factor in explaining honey bee declines. (Proceed with caution: This is a publication by an advocacy group, not a peer-reviewed journal.)  The group says it has examined studies in the U.S. and Europe and that they "have shown that small amounts of neonicotinoids—both alone and in combination with other pesticides—can cause impaired communication, disorientation, decreased longevity, suppressed immunity and disruption of brood cycles in honeybees."

Companies that make the chemicals have disputed many of the studies, but the Network claims that there's enough evidence to compel regulators to act. Tomorrow, California's Assemble Agriculture Committee will consider a plan to come up with a way to protect bees.