The information in this state update was provided by Dr. David James, email@example.com. Please contact him for additional information about the update.
Washington State is usually the final destination for the majority of western monarchs migrating north in spring. A few make it into British Columbia by up to 100 miles but many make Washington their summer-breeding home in most years. Most abundance occurs on the eastern side of the state although a few migrate north through western Washington and will stop and lay eggs if they encounter milkweed.
Showy milkweed is the dominant milkweed species in Washington and it is common to abundant along roadsides and in riparian areas of eastern Washington. The first monarchs are seen in early June each year in Washington and produce at least two generations. Monarchs eclosing in August may join the migrating generation and those eclosing in September certainly do.
By early October, most monarchs have left Washington State and are en route or have arrived at overwintering sites in California. A few individuals migrate in a different direction towards the south-east, through Utah and may end up overwintering in Mexico.
There are no monarchs left in Washington. This is always true in November because our summer resident monarchs have always migrated south by now. However, this year it sadly was also true of the summer. For the first time in the 20 years that I have been keeping records on monarch incidence and abundance in Washington State, there were virtually no monarchs present. I say ‘virtually’ because two were sighted near the Tri-Cities but the absence of others in nearby breeding areas suggests that these two may have been releases from a local butterfly breeder.
No confirmed sightings were made north of the Tri-Cities. A well-researched summer breeding site for monarchs in central Washington, which as recently as 2016 supported hundreds of monarchs, was devoid of monarchs this summer. Washington remains an excellent place for summer monarchs! Milkweed is plentiful and abundant in many places east of the Cascades right up to the Canadian border. Our lack of monarchs has nothing to do with a shortage of milkweed within the state.
Washington monarchs largely originate from overwintering populations in California, so how monarchs are doing in California dictates whether we see them in Washington.
Currently of course, overwintering counts in California are at record lows and it is only since this number has been less than 30,000, that Washington State has become monarch-free. Overwintering numbers need to rise above 30,000 for monarchs to reappear in Washington again.
Given the predicted low overwintering population again this year, it may sadly be some time before we see monarchs in Washington again.
Abundant Showy milkweed at a central Washington monarch breeding site that went unused in 2020.
Hands used for crime now nurturing a struggling species (KXLY News, September, 2018)
Monarch Butterflies in the Pacific Northwest Facebook page