Read more at The Guardian

Here’s a summary of the article about the 2024 monarch butterfly die-off:

• Pesticides Caused Die-Off: A mass die-off of monarch butterflies in California in early 2024 was likely caused by exposure to pesticides, according to new peer-reviewed research.
• Signs of Poisoning: Hundreds of butterflies were found dead or dying, exhibiting twitching, which are common signs of neurotoxic pesticide poisoning.
• Widespread Contamination: Testing on a small sample of 10 butterflies found an average of seven different pesticides in each insect, with levels suspected to be lethal. All butterflies showed high levels of the same three pyrethroids, a widely used class of pesticides.
• Rare Evidence: The study provides rare, direct evidence of pesticide exposure in a wild butterfly population, helping to fill a gap in research that has long pointed to pesticides as a key factor in monarch population declines.
• Potential Sources: The die-off occurred near the Pacific Grove Monarch Sanctuary. Researchers believe the source of the poisoning was likely a nearby residential application of pyrethroid pesticides, which are not typically reported.
• Synergistic Effect: The combined presence of multiple pesticides may have a synergistic effect, making them even more toxic to the butterflies.
• Call for Action: The study’s lead author, Staci Cibotti, advocates for reducing pesticide use, especially around critical migratory sites, to prevent immediate losses and aid in the long-term recovery of the monarch population.