The western bumblebee, which plays an important role in supporting agriculture and wildlife species, has experienced a 93 percent decline on the continental U.S. over the past two decades, according to estimates by scientists from a study published last June.

Native bees such as the western bumblebee are the most effective pollinators of wildlife foods like huckleberries -- a staple for bears -- along with the fruits and vegetables found in grocery stores, providing agricultural pollination services worth $20 billion every year.

“One in every three bites of food we eat depends on bees and other pollinators,” the Natural Resources Defense Council states.

Plants need pollinators like bees to spread pollen to female parts of flowers in order to produce fruit and bumblebees play a vital role in supporting human agriculture through the fuzz on their body and a strategy called buzz-pollination. Only pollinators that buzz the right amount can extract the pollen from flowers of tomatoes, potatoes, blueberries and eggplants, and other such plants that keep their pollen hidden.

“In North America, you are nearly 50 percent less likely to see a bumblebee in any given area than you were prior to 1974,” National Geographic reports.

A large contributor in this decline in population is climate change, which influences the availability of flowers bees depend on, and can cause them to overheat. Areas that have become hotter or experienced extreme temperature swings, now have less bumblebees, according to a study from last February.

Other factors threatening bees include habitat loss, pesticides and invasive insects and plant species. 

Practices to help bees include planting native flowers for bees to feed on; avoiding neonicotinoid pesticides, which can harm bees even at low exposure; waiting till spring before removing leaf litter -- which may be a spot queens to rest in during winter.

Another way to contribute is by joining initiatives such as bumblebeewatch.org, an app for individuals to document bumblebees they encounter as part of a nationwide collaborative effort to conserve the species.