The Monarch monitoring “Bioblitz” event on August 4, 2026, visited the Novato Traffic Island Habitat in Pacheco Valle to count caterpillars and monarch butterflies (Danaus plexippus). The data collected was for the annual international Monarch Bioblitz.
Volunteers from Pacheco Valle Biodiversity joined with the Marin Monarch Working Group (MMWG) and Home Ground Habitats in all the BioBlitz fun. Jackie Garcia did a wonderful job of talking about the Marin Median Project to the group on the day of the field trip. The Pacheco Valle median garden is becoming a serious hot spot for monarchs!
Results have been added to the Western Monarch Milkweed Mapper on iNaturalist.
Marin Median Project – Pacheco Valley Median Statistics
- 116 eggs (Officially observed; 150+ likely present)
- 5 caterpillars
- 7 butterflies
Where to see Monarchs Fall/Winter 2026 in California
As temperatures drop, days shorten, and milkweed plants die back, monarchs journey from across North America to special locations along the Pacific coast and central Mexico.
Whether you’re a lifelong nature enthusiast or a curious first-time visitor, November and December offer the perfect opportunity to witness monarch aggregations up close.
The Marin Monarch Working Group has more on the MMWG website.
Visit the Xerces Society for Everything You Need To Know About Visiting Overwintering Monarchs.
October 2026 Update from Marcia Basalla
Sunday October 4, 2026 was quite a day at the Pacheco Valle traffic island.
We counted about 50 monarch larvae of all sizes! They were found mainly on the Narrow Leaf Milkweed.
There is even a “volunteer” stand of Milkweed across the street west of the traffic island. It was covered with about 40 larvae. It has been there for the past two seasons. I call it the “renegade.”
