The discovery of 25,000 dead bumblebees in an Oregon parking lot is a dramatic reminder that bee populations around the world are in big trouble. There are fewer domesticated honeybees now than at any time in the last 50 years, while the numbers of four species of bumblebees have dropped by 90 percent over the last few decades.

In this particular case, the culprit is probably pesticide sprayed on blooming European linden trees, which the bees were clustered around. Scott Hoffman Black, executive director at the Xerces Society for Invertebrate Conservation, calls it the "largest known kill of bumblebees."

The fact that it happened in a Target parking lot only made it more tragic, says Black:

We need to spotlight this as a real-world lesson in the harm these toxic chemicals are causing to beneficial insects. It would be especially alarming to find out whether pesticides are the cause in this case because the linden trees are not even an agricultural crop. Any spraying that happened would have been done for purely cosmetic reasons. [Portland Tribune]

The Xerces Society notes that 25,000 bumblebees equals around 150 colonies. That is bad news for Oregon's blueberry and raspberry farms, which depend on bumblebees for pollination.

Even more alarming is the large-scale deaths of honeybees, blamed on something called colony-collapse disorder (CCD). In the 1940s, there were around 5 million bee colonies in the United States. Today, there are only 2.5 million. The problem made headlines in 2006, when farmers began reporting that 30 to 90 percent of their colonies were dying during the winter.

It's not entirely clear what is causing CCD. Scientists have named a number of culprits, including fungi, viruses, varroa mites, and more. Neonicotinoid pesticides have also been singled out by researchers.

In Europe, three types of neonicotinoids are being banned from flowering crops, which attract bees. No such ban exists in the United States.

What does this all have to do with the U.S. economy? Bees add $15 billion of value to U.S. crops every year by pollinating them, according to the USDA, which added that although "honeybees would not disappear entirely" at the current rate that they are dying at, "the cost of honeybee pollination services would rise, and those increased costs would ultimately be passed on to consumers through higher food costs."