Monarch butterflies, once common sights across North America, have disappeared so quickly they might become an endangered species in the next year.

Habitat loss due to agriculture has caused the insect’s population to fall 90% in 20 years, prompting the U.S. Fish and Wildlife Service to consider protecting monarch butterflies under the Endangered Species Act, Reuters reported Monday.

Farming practices including as widespread pesticide use and herbicides have destroyed milkweed plants, on which the butterflies lay eggs and hatch larvae.

The review of the butterflies’ status came after conservationist groups filed to the Fish and Wildlife Service requesting federal protection for the butterflies. The agency said the conservationists’ claim “presents substantial information indicating that listing may be warranted,” and that the agency will need about one year to complete the review.

[Reuters]

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