The U.S. Fish and Wildlife Service says the designation took effect Tuesday, making the rusty-patched bumblebee the first bee species in the continental U.S. to receive federal protection under the Endangered Species Act.
Advocates say the bee has disappeared from about 90 per cent of its range in the past 20 years. Bees are crucial for pollinating crops and wild plants.
The listing was announced in January and had been scheduled to take effect Feb. 10. But the Trump administration ordered a last-minute review and postponed the listing until Tuesday. Some environmentalists had feared the designation could be cancelled.
The Natural Resources Defence Council filed a lawsuit over the delay, saying it had been ordered without required public notice and comment.