Our country's most efficient pollinator, the domesticated honeybee, is in decline. We talked with Dennis vanEngelsdorp, Ph.D.-an entomologist at the University of Maryland and one of the first to see honeybees were in trouble 10 years ago-about why we should be concerned.

Why are honeybees in decline?
We continue to see high levels of mortality; whole hives are disappearing. Each year, we continue to lose an average of 30% of our colonies. We think it's caused by the equivalent of bee flu. When bees are sick they leave the hive to prevent other bees from getting sick. The big question is, why are bees succumbing to flu and to a combination of other viruses and pathogens? The three biggest factors are increasing pesticides, varroa mites and poor nutrition; all weaken the bees' immune systems. As land is developed, bees are having a harder time finding food. And pesticide use is pervasive-in agriculture and at our homes. In one study, we found 21 different types of pesticides in pollen. Per acre, people use more pesticides on yards and gardens than on any agricultural crop.

What about the recent effort to ban a class of pesticides called neonicotinoids?
It won't have much impact. This class of synthetic pesticides is banned in Europe, but they're not the only chemicals weakening bee health. There are a lot of others that may have just as much or more of an effect. In a recent study, for example, we found that two widely used fungicides are showing up in bee pollen and making bees more than two times as susceptible to a fungal infection. Another study found that exposure to pyrethroids [which constitute most commercial household insecticides] stunts bee growth, causing them to be less effective at foraging.

Should we be worried about other bees?
Yes. Domesticated honeybees, which were brought to the Americas in the 1800s, are used to pollinate many commercial crops. But we need native bees too. We need squash bees for squash, bumblebees for blueberries. Yet three species of bumblebee have gone extinct over the last 20 years. Studies suggest that restoring habitat near farms to nurture native bees would increase crop yields. There are about 4,000 species of bees native to the United States. And most need our help.

The Foods We'd Lose

If we did not have bees, our diet would be a lot less diverse, and pricier. About 33% of what we eat comes from food pollinated by bees. Almonds, asparagus, apples, blueberries, avocado, broccoli, onion, cherries and cucumber are just a few of the foods we'd say goodbye to. The shortages wouldn't just affect fruits and veggies; even milk would become scarce. That's because the protein-rich alfalfa that dairy cows eat needs pollinators to produce seed. Fewer bees leads to smaller harvests and higher food costs.

What You Can Do to Help

Buy Local Honey: It supports local beekeepers. Plus, it's good for the environment: compared to other sweeteners, it requires the least amount of carbon to get to your table, says vanEngelsdorp.

Garden: Make your outdoor space pollinator-friendly. Visit to find pollinator-friendly plants. Pick a variety of plants so you can provide blooms throughout the season, and skip commercial pesticides, herbicides and fungicides in favor of bee-friendly alternatives, like insecticidal soaps. Check out

Make a Home: Nest sites-such as bamboo tubes, boxes or hollow logs-can help attract and protect native bees (most are stingless!). Many, like leafcutter bees-great pollinators of summer veggies and herbs-are declining because they can't find enough nesting sites.

Go Organic: Vote with your fork-to reduce the use of synthetic pesticides and other harmful chemicals-by buying organic when possible. While some organic pesticides can harm pollinators-such as pyrethrin and spinosad-most are still a safer and better choice for bees.