- Author: Kathy Keatley Garvey
What we've been waiting for all season...
A migratory monarch butterfly fluttered into our Vacaville garden at noon today (Tuesday, Sept. 17) and nectared on a Mexican sunflower, Tithonia rotundifola.
Then she treated us to a butterfly ballet.
The Danaus plexippus touched down, nectared, shot up, dropped down, and did it all over again, while male territorial longhorned bees tried to make her stay short.
But she hung around for and hour.
Wings up...and she was gone.
And then another flashed by...
It's migratory monarch season.
- Author: Kathy Keatley Garvey
You've heard folks call insects "big 'ol bugs" (often in astonishment or terror), right?
But have you ever seen a "bigeyed bug on a monarch butterfly?"
Bigeyed bugs, Geocoris spp., are beneficial insects, "found mostly on low-growing plants, including many field and row crops and in gardens," according to the UC Statewide Integrated Management Program (UC IPM). "Adults and nymphs feed by sucking prey's body contents through their needlelike mouthparts. Bigeyed bugs feed on bug nymphs, flea beetles, insect eggs, small caterpillars, and all stages of aphids, mites, and whiteflies. Bigeyed bugs also feed harmlessly on pollen, seeds, and plant juices and are not plant pests."
And Wikipedia tells us: "Big-eyed bugs, like other true bugs, have piercing-sucking mouthparts and feed by stabbing their prey and sucking or lapping the juices. Although their effectiveness as predators is not well understood, studies have shown that nymphs can eat as many as 1600 spider mites before reaching adulthood, while adults have been reported consuming as many as 80 mites per day."
So, it's Jan. 4, 2024, and here's this bigeyed bug resting in a patch of blanket flowers (Gaillardia) in our Vacaville pollinator garden. Then it's briefly crawling up the wing of a monarch that's nectaring on the flowers. (Yes, fall and winter monarch breeding does occur here in central California, according to butterfly guru Art Shapiro, UC Davis distinguished professor emeritus. He recorded a monarch in flight on Jan. 19, 2020 in Sacramento, but even earlier than that--UC Davis professor Louie Yang of the Department of Entomology and Nematology spotted a monarch flying Jan. 8, 2012 in east Davis. We saw a monarch in flight on Dec. 16, 2023 in Vacaville.)
So, what happened to the bigeyed bug and the monarch butterfly? They vanished. Both of them.
Wings up?
- Author: Kathy Keatley Garvey
The monarch migration is well underway. The iconic butterflies fluttering into California from the Pacific Northwest engage in "nectar stops" to fuel their flight to their overwintering sites along coastal California.
They are not the only ones seeking nectar.
Monarch: "Sweet! Look what I found! Nectar! Did someone plant this patch of zinnias just for me?"
Honey Bee: (Buzzing in) "Share, Monarch! I need some of that nectar to take home to my colony. Winter's coming and my queen and my sisters need more nectar to tide us over until spring."
Monarch: "Sorry, Bee. I'm on a tight flight schedule and you can always get your nectar tomorrow."
Honey Bee: "Maybe if I buzz your wings, you'll leave!"
Monarch: (Wings up) "I can take the hint, but I'll be back!"
"The annual migration of North America's monarch butterfly is a unique and amazing phenomenon. The monarch is the only butterfly known to make a two-way migration as birds do. Unlike other butterflies that can overwinter as larvae, pupae, or even as adults in some species, monarchs cannot survive the cold winters of northern climates. Using environmental cues, the monarchs know when it is time to travel south for the winter. Monarchs use a combination of air currents and thermals to travel long distances. Some fly as far as 3,000 miles to reach their winter home!...Monarchs living west of the Rocky Mountain range in North America overwinter in California along the Pacific coast near Santa Cruz and San Diego...Monarchs roost in eucalyptus, Monterey pines, and Monterey cypresses in California."--U.S. Forest Service
"A three-week count in November and December 2022, conducted over 272 sites in coastal California by the Portland-based Xerces Society for Invertebrate Conservation, tallied 335,479 of the orange-and-black iconic butterflies, an increase of 36% over the 247,237 counted the previous year. More importantly, the rebounding species (Danaus plexippus) hit an all-time low of 2,000 in 2020, leaving biologists concerned it would disappear from North America."--Los Angeles Daily News.
- Author: Kathy Keatley Garvey
That's the abstract of UC Davis community ecologist Louie Yang's review article published June 26 in the journal, Current Opinion in Insect Science. Yang, a Department of Entomology and Nematology professor who researches monarch butterflies, suggests three broad guidelines for western monarch conservation.
The western monarch population overwinters along the California coast. Estimated at 4.5 million in the 1980s, it has dropped significantly over the past five years, the professor related, noting an “86% single-year population decline in 2018, an overwintering population of less than 2000 butterflies in 2020, and an unexpected >100-fold increase in 2021."
Yang defined the western monarch population as occupying "a geographically distinct region of North America west of the Rocky Mountain...Ongoing climate change has made the western monarch range warmer, drier, and more prone to heatwaves, wildfires, and winter storms with complex effects on their ecology. Land development and changes in the structure of landscape mosaics have modified both the breeding and overwintering habitats of western monarch butterflies, changing the spatial distribution of resources and risks across their range. Shifts in agricultural and horticultural practice have changed the nature of potentially deleterious chemicals in the environment, including novel herbicides and insecticides."
His three suggestions:
- "First, we should continue to support both basic and applied monarch research. This includes efforts to better understand fundamental aspects of monarch biology, studies to examine the ecological factors that limit monarch populations in the West and efforts to improve more targeted adaptive management and monitoring efforts. Basic research in monarch biology and ecology improves our understanding of this complex system and can inform conservation actions in profound and unexpected ways. In turn, applied research can address recognized gaps in knowledge that would otherwise limit available strategies for conservation planning and management."
- "Second, recognizing the limits of our current understanding, we should follow the precautionary principle to minimize the risk of counterproductive action. The complexity of this system makes it difficult to anticipate or assume future changes in behavior, species interactions or population dynamics. In practice, this may mean prioritizing efforts to better understand and facilitate existing mechanisms of ecological resilience and recovery over direct actions to manipulate or augment the population with less certain consequences. More broadly, this approach would probably emphasize common sense approaches to mitigate the widely recognized upstream drivers of global change (e.g., climate change and land use change), rather than those requiring a detailed understanding of their complex, interactive effects on species-specific ecologies further downstream."
- "Third, we should work to improve, protect and maintain the resources required throughout the complex monarch life cycle. In part, this likely means prioritizing conservation efforts that target the times and places that are likely to have the greatest positive effects, building on the common ground of available science. In the case of western monarchs, this includes protecting current and future overwintering habitats, the resources required for population expansion in the early season, and the resources required for the fall migration. Recognizing the potentially widespread and pervasive effects of pesticides, this could also mean efforts to develop more ecologically realistic and relevant metrics for the regulation of environmental chemicals."
Editors of the journal, Current Opinion in Insect Science, describe it as "a new systematic review journal that aims to provide specialists with a unique and educational platform to keep up–to–date with the expanding volume of information published in the field of insect science."
Yang's research is supported by a National Science Foundation award. He was a guest on National Public Radio's Science Friday in February 2022. Listen to the interview here.
All year long, we've been waiting for those majestic monarchs to visit our pollinator garden in Vacaville, as they have in the past 10 years or so. One year (2020), they deposited more than 300 eggs on our milkweed.
But this year?
Zero. Zilch. Nada.
Where are you?
Dawn. Noon. Dusk.
Where are you?
Nothing has fluttered in and out except the Western tiger swallowtails, Gulf Fritillaries, fiery and common-checkered skippers, cabbage whites, buckeyes, mourning cloaks, and gray hairstreaks.
The milkweed grew, blossomed and went to seed. Ditto the Mexican sunflowers (Tithonia rotundifola). But the patch of Mexican petunia (Ruellia brittoniana) is thriving. The plant is a plucky perennial with purple, petunia-like flowers.
Purple, the color of royalty...a place where a monarch can reign supreme.
And that's exactly what happened today in the petunia patch at 3 p.m. A monarch fluttered in and sipped a little nectar. I almost missed it, as I was observing the Gulf Fritillary activity around the passionflower vine--the males chasing the females, the females laying eggs on the tendrils and leaves, and caterpillars munching the leaves.
The monarch didn't stay long, and I was too far way to move closer, but the Nikon Z-7 with its 105mm macro lens and its 45.7 megapixels, let me know that it was, indeed, one of those majestic monarchs we've been missing.
Hallelujah!
Washington State University entomologist and monarch researcher David James was right. On Aug. 31, he said I'd be seeing monarchs in a few weeks as they're leaving the Pacific Northwest (PNW) on their way to their overwintering sites along the California coast. (See Sept. 2 Bug Squad blog)
"The numbers we are seeing in the PNW this summer are consistent with numbers I've seen in summers past when theoverwintering population was approximately 250,000 as it was last winter," he related Aug. 31. "Last summer (2021) I verified approximately 60 Monarch sightings in the PNW. This summer, I have had approximately 500 verified reports. So, I think we have seen an 8-10 fold increase in Monarch numbers this summer in the PNW. The majority have been in Oregon, followed by Idaho, Washington and British Columbia. There are also positive reports of good numbers of Monarchs in Utah, Nevada and eastern California."
To track migratory monarchs, citizen scientists in the David James' research program affix a tag on the discal cell (underside of the hind wing). (The tag does not interfere with its flight.) This year James handed out 2000 tags to citizen scientists in southern Oregon.
Now, maybe we'll see another tagged traveler like the one we photographed in 2016. The scenario: One of his citizen scientists, Steve Anderson of Ashland, Ore., tagged a male monarch on Aug. 28, 2016 that stopped for nectar in our Vacaville pollinator garden on Sept. 5, 2016. The tag read “Monarch@wsu.edu A6093." It hung around for five hours. (See Bug Squad blog and WSU news story)
"So, assuming it didn't travel much on the day you saw it, it flew 285 miles in 7 days or about 40.7 miles per day," James told us back in 2016. "Pretty amazing. So, I doubt he broke his journey for much more than the five hours you watched him--he could be 100 miles further south by now."
Meanwhile, watch for monarchs! What to do if you see a WSU-tagged monarch? Photograph it, if you can, and contact David James at david_james@wsu.edu or the PNW Facebook page. Also, report any Monarch sightings to iNaturalist and Journey North.