Welcome Back Good GROWer,
the numbers are in and it appears the western monarchs are off to another (deeply troubling) slow start this spring.
During the 2025 winter season, only 12,260 butterflies were counted throughout 249 overwintering site in California. That’s roughly the crowd size of a poorly attended MLB game ⚾️…now imagine those fans were all the size of a tiny monarch butterfly.
According to Emma Pelton, a senior conservation biologist at Xerces Society, “Western monarchs are in serious trouble…the migration is collapsing.”
Experts say that several factors are contributing to the low numbers including habitat loss, pesticides, and climate change.
One factor I rarely see mentioned is often brought to my attention from those trying to raise monarchs out west…tachinid fly parasites ⬅️. In recent years, more western raisers have reported bringing in caterpillars only to have 100% of them already parasitized by flies.
Biological pest control is viewed by many as a safe alternative to pesticides. However, flies released en masse by farmers trying to protect crops, could also be having a devastating affect on monarchs and other unintended butterfly caterpillars.
The counting was done in November and December when monarchs are most likely (at least historically) to be clustering in trees.
While there isn’t much positive news here for western monarchs and their supporters, there are still western organizations, businesses, and communities working hard to bring them back from the brink…
🦋 Western Monarch Resources❓🌿🐛
This page has just been updated with the links to the current monarch count and has 13 resources trying to help the western monarchs. Please feel free to leave a comment in the box at the bottom of the linked blog post if you know of other helpful resources for western monarchs:
The eastern monarch population estimate (the monarchs that migrate to Mexico) has not been released yet. Typically, the eastern estimate is released by late February or early March. I will be sure to report the eastern population estimate in this newsletter when those numbers are available…
Until next time,
Tony your Butterfly Guide 🦋
