Don't tell the honey bees.
They will forage where they want to--whether it's on bee balm, a dandelion or that controversial tropical milkweed, Asclepias curassavica.
Just before we cut back the tropical milkweed for the season, the honey bees got their last hurrah--the last bit of nectar for the year.
Why cut back tropical milkweed? Scientific research shows that this plant disrupts the monarch migration patterns when it's planted outside its tropical range, and can lead to the spreading of OE, orophryocystiselektroscirrha, a protozoan parasite that infects monarch and queen butterflies. So we gardeners cut it back AFTER the monarchs have quit laying their eggs for the summer (or early fall) and BEFORE the monarch migratory season.
Honey bees, however, do love that milkweed. (Note that some scientists, conservation organizations and horticulturists urge folks NOT to plant the non-native tropical milkweed, and if they do, cut it back before the migratory season. See post from Xerces Society of Invertebrate Conservation.)
Connie Krochmal's article on "Milkweed as Honey Plants" in the Aug. 23, 2016 edition of Bee Culture magazine points out just how much bees love milkweed.
"Very fond of milkweed blossoms, bees will desert other flowers when these are available. The plants provide a good nectar flow. Bees discard the pollen. Assuming enough plants are available, milkweeds can bring a good crop of honey."
Milkweed, Krochmal writes, "are major bee plants in the North Central states, the Northeast, Southeast, the Plains, and the mountainous West." The honey is typically light colored and mild-flavored, she added.
"Generally, milkweeds are considered beneficial to bees. However, there are potential negative aspects to milkweed flowers. It is conceivably possible for bees and other small pollinators to become trapped in a blossom. Also, the sticky pollen masses might cling to a bee's head or legs, thereby affecting her mobility or appearance."
Yes, it does. We've seen many a bee struggle to free herself from the pollinia. Some lose their legs. Some perish.
But that nectar--that nectar--the bees keep coming back for more.
Monarchs lay their eggs on the underside of milkweed leaves--generally--but we've seen them on stems and on the leaf edges. They usually deposit a single egg beneath the leaf, but we've spotted as many as four on one leaf. They secrete a glue so the egg will adhere.
Color? They're a creamy yellow with narrow longitudinal ridges from the top to the bottom. Size? About 0.9 to 1.2 mm long, or about the size of a pinhead.
They hatch about 3 to 4 days after they're laid. Then you'll see the black-headed tiny larva or caterpillar eating its shell before it begins devouring the leaf.
Some folks confuse the sap-sucking yellow oleander aphids with the monarch eggs. Or the yellow eggs of the lady beetle, aka ladybug. So we took a few images of them.
In our family pollinator garden in Vacaville, we've collected about 250 monarch eggs or caterpillars this year, and the mamas are still laying eggs! We're not the only ones who like monarchs. We try to collect the eggs before the predators and parasitoids get them. Predators include lady beetles (ladybugs), spiders, milkweed bugs, lacewings, and wasps. Tachinid flies and other parasitoids lay their eggs in or on the immature monarchs or deposit their eggs on a leaf that the caterpillar eats. The fly larvae develop inside the living host, killing it. Note: tachinid flies are considered beneficial insects when they lay their eggs in such pests as cabbageworms.
We grow five species of milkweed:
- Tropical: Asclepias curassavica
- Narrowleaf: Asclepias fascicularis
- Showy: Asclepias speciosa
- Butterfly weed: Asclepias tuberosa
- Swamp milkweed: Asclepias incarnata
But back to the question: how can you tell the difference between an oleander aphid and a monarch egg? They are so tiny and both are yellow! Basically, the aphid has legs and it moves! Some aphids are winged and fly. Another clue: aphids cluster together; you won't find monarch eggs in a cluster.
Note that the lady beetle lays her eggs in clusters, so if you find a cluster of eggs, those aren't monarch eggs.
Professor Elizabeth Crone of Tufts University who researches monarchs (as well as bumble bees), drew a standing-room only crowd when she presented a UC Davis Department of Entomology and Nematology seminar on the decline of Western monarchs.
UC Davis professor Neal Williams, a pollination ecologist who researches native bees, praised her "fearless perspective in the use of statistics; I value her insights." Williams has collaborated with her "off and on" for 20 years.
Crone, who just finished a six-month research sabbatical at UC Davis, says her work centers on population ecology, especially of plants and insects, and plant-animal interactions. "Specifically, I am interested in how environmental changes translate to changes in population dynamics: For example, is there a simple, linear matching of changes in resources to abundance of consumers, or do interactions among individuals and species moderate these responses? Much of my research also involves developing novel quantitative approaches to predict long-term dynamics from small scale observations and experiments. Current projects include studies of butterflies, bees, perennial wildflowers, sugar maples, and acorn-granivore interactions."
In her UC Davis seminar, Crone pointed out that the population of Western monarchs, which overwinter along the California coast, dropped from an estimated 4.5 million in the 1980s to less than 30,000 in the winter of 2019.
After the monarchs leave their overwintering sites in February and head inland, "we don't really know where they are in spring," Crone lamented. "There's not a lot of records of where monarchs are in spring. That's why we're trying to draw on citizen scientists to help us find monarch butterflies in the spring."
Crone is a member of a team of researchers, led by Cheryl Schultz, biology professor at Washington State University, who are recruiting the public, aka citizen scientists, to report sightings of monarchs from Feb. 14 through April 22, Earth Day. The project is called the Western Monarch Mystery Challenge.
To participate in the Western Monarch Mystery Challenge:
- If you see a monarch outside of overwintering groves, take a picture! (Don't worry, it can be far away and blurry.)
- Report it to iNaturalist (the app is free) OR email MonarchMystery@wsu.edu and be sure to include date, species and location for both methods
- You will automatically be entered to win a variety of prizes every week you report a sighting.
All data will be added to the Western Monarch Milkweed Mapper, a year-round community science project tracking milkweeds and monarchs in the West.
Crone told the UC Davis crowd that "we need to understand the basic biology throughout the life cycle....So from a conservation perspective, we know that we need to protect and restore overwintering sites on the coast of California...It also helps to improve summer habitat both for its own sake and maybe to mitigate losses. It other places, this includes planting your own pollinator gardens. It includes minimizing ;pesticide use society-wide."
It's not just agriculturists who use pesticides, said Crone, noting that "California tracks pesticide use." She showed a database that indicated 25 percent of the state's total pesticide use is for non-agricultural uses. This includes pesticide applications in parks, roadsides and golf courses, she said. "That doesn't include people who go to Lowe's or Home Depot and pick up a can of insecticide to prevent the aphids from eating their roses. And read the label and it says, 'Why don't you just spray every week so you never see aphids at all?' So we should be very aware that pesticides are everywhere in our landscape, and a lot of us are using them without thinking about them. And anything we can do to minimize pesticides has got to be good for nearly all insects."
From an applied ecology perspective, Crone considers her biggest accomplishment "helping the Fender's blue butterfly move from being listed as endangered to nearly ready for down-listing. From a basic ecology perspective, I figured out the ecological interpretation of variance terms in mixed models as estimates of spatial heterogeneity and environmental stochasticity, and worked out one of the best examples of how mast-seeding species are synchronized by their pollinators."
"It's an exciting time to be an ecologist," Crone said. "Because the puzzle of linking natural history and theoretical ecology to guide conservation is really intellectually interesting, even from an academic perspective. And it also makes me optimistic."
"We did it with Fender's blue butterfly," she told the crowd. "Maybe we can help prevent other insect populations from being at risk of extinction."
To listen to her talk, access this newly uploaded video from ucdavis.edu/media. Access is free.
Take the case of a male monarch reared, released and tagged by Steven Johnson in a Washington State University citizen-science project operated by WSU entomologist David James. Johnson tagged and released the monarch on Sunday, Aug. 28, 2016 in Ashland, Ore. Seven days later, on Sept. 5, it fluttered into our family's backyard pollinator garden in Vacaville, Calif., where we photographed it.
"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 said. "Pretty amazing." (See Bug Squad blog)
But how do monarchs know when to migrate? You can find out when you attend the UC Davis Bohart Museum of Entomology open house on Saturday, Jan. 18 from 1 to 4 p.m. in Room 1124 of the Academic Surge Building, Crocker Lane.
Doctoral student Yao Cai, a fourth-year doctoral student in the Joanna Chiu lab who studies circadian clocks in insects, will relate how monarchs know when to migrate. “Using Drosophila melanogaster (fruit fly) and Danaus plexippus (monarch butterfly), as models, we seek to understand how these insects receive environmental time cues and tell time, how they organize their daily rhythms in physiology and behavior, such as feeding, sleep and migration (in monarch butterfly)," he says.
Cai is one of six doctoral students who will be showcasing their research. The event is free and family friendly.
Visitors not only will have the opportunity to talk to graduate students about their research and glean information about insects, but will be able see their work through a microscope. In fact, eight microscopes will be set up, Yang said.
In addition to Cai, doctoral students participating and their topics:
Ants: Zachary Griebenow of the Phil Ward lab, UC Davis Department of Entomology and Nematology
Assassin flies: Charlotte Herbert Alberts, who studies with major professor Lynn Kimsey, director of the Bohart Museum, UC Davis Department of Entomology and Nematology
Bats (what insects they eat): Ecologist Ann Holmes of the Graduate Group in Ecology, Department of Animal Science, and the Genomic Variation Laboratory, who studies with major professors Andrea Schreier and Mandi Finger.
Bark Beetles: Crystal Homicz. who studies with Joanna Chiu, UC Davis Department of Entomology and Nematology and research forest entomologist Chris Fettig, Pacific Southwest Research Station, USDA Forest Service, Davis.
Forensic entomology: Alexander Dedmon, who studies with Robert Kimsey, UC Davis Department of Entomology and Nematology
Some doctoral students also will deliver PowerPoint presentations or show slides. The projects:
“Did you know that between 1987 and 2017 bark beetles were responsible for more tree death than wildfire?” asks Crystal Homicz, a first-year doctoral student. “Bark beetles are an incredibly important feature of forests, especially as disturbance agents. My research focuses on how bark beetles and fire interact, given that these are the two most important disturbance agents of the Sierra Nevada. At my table, I will discuss how the interaction between bark beetles and fire, why bark beetles and fire are important feature of our forest ecosystem, and I will discuss more generally the importance of bark beetles in many forest systems throughout North America.
“I will have several wood samples, insect specimens and photographs to display what bark beetle damage looks like, and the landscape level effects bark beetles have. I will also have samples of wood damage caused by other wood boring beetles and insects. My table will focus widely on the subject of forest entomology and extend beyond beetle-fire interactions.”
Visitors, she said, can expect to leave with a clear understanding of what bark beetles are and what they do, as well as a deeper understanding of the importance of disturbance ecology in our temperate forests.
Charlotte Alberts, a fifth-year doctoral candidate, will display assassin flies and their relatives, as well as examples of prey they eat and/or mimic. Visitors can expect to learn about basic assassin fly ecology and evolution. Alberts studies the evolution of assassin flies (Diptera: Asilidae) and their relatives.
“Assassin flies are voracious predators on other insects and are able to overcome prey much larger than themselves,” she said. “Both adult and larval assassin flies are venomous. Their venom consists of neurotoxins that paralyze their prey, and digestive enzymes that allow assassin flies to consume their prey in a liquid form. These flies are incredibly diverse, ranging in size from 5-60mm, and can be found all over the world! With over 7,500 species, Asilidae is the third most specious family of flies. Despite assassin flies being very common, most people do not even know of their existence. This may be due to their impressive ability to mimic other insects, mainly wasps, and bees.”
For her thesis, she is trying to resolve the phylogenetic relationships of Asiloidea (Asilidae and their relatives) using Ultra Conserved Elements (UCEs), and morphology. "I am also interested in evolutionary trends of prey specificity within Asilidae, which may be one of the major driving forces leading to this family's diversity."
Ecologist Ann Holmes, a fourth-year doctoral student, is studying what insects that bats eat. "I will be talking about my research project that looks at insects eaten by bats in the Yolo Bypass. The insects eat crops such as rice, so bats provide a valuable service to farmers. Hungry bats can eat as much as their own body weight in insects each night."
"Visitors can expect to learn how DNA is used to detect insects in bat guano (poop)." "Insects in bat poop are hard to identify because they have been digested, but I can use DNA to determine which insects are there," she said. "We care about which insects bats eat because bats are natural pest controllers. With plenty of bats we can use less pesticide on farms and less mosquito repellent on ourselves."
Zachary Griebenow, a third-year doctoral student, will be showcasing or discussing specimens of the ant subfamily Leptanillinae, most of them male. “I will be showing specimens of the Leptanillinae under the microscope, emphasizing the great morphological diversity observed in males and talking about my systematic revision of the subfamily," he said. "In particular, I want to explain how the study of an extremely obscure group of ants can help us understand the process of evolution that has given rise to all organisms."
Forensic entomologist Alex Dedmon, a sixth-year doctoral student, will display tools and text and explain what forensic entomology is all about. "My research focuses on insect succession. In forensic entomology, succession uses the patterns of insects that come and go from a body. These patterns help us estimate how long a person has been dead. Visitors can expect to learn about the many different ways insects can be used as evidence, and what that evidence tells us."
Other Open House Activities
The family craft activity will be painting rocks, which can be taken home or hidden around campus. "Hopefully some kind words on rocks found by random strangers can also make for a kinder better future,” said Yang.
In addition to meeting and chatting with the researchers, visitors can see insect specimens (including butterflies and moths), meet the critters in the live “petting zoo” (including Madagascar hissing cockroaches, walking sticks and tarantulas) and browse the gift shop, containing books, insect-themed t-shirts and sweatshirts, jewelry, insect-collecting equipment and insect-themed candy.
The Bohart Museum, directed by Professor Lynn Kimsey and founded by noted entomologist Richard M. Bohart (1913-2007), houses a global collection of nearly eight million specimens. It is also the home of the seventh largest insect collection in North America, and the California Insect Survey, a storehouse of insect biodiversity.
The insect museum is open to the public Mondays through Thursdays from 9 a.m. to noon and 1 to 5 p.m., except on holidays. More information on the Bohart Museum is available on the website at http://bohart.ucdavis.edu or by contacting (530) 752-0493 or firstname.lastname@example.org.
If you've been finding more milkweed bugs than monarchs on your milkweed, join the crowd.
Monarchs are scarce--at least around Solano and Yolo counties--but milkweed bugs are quite plentiful. Sometimes you see them massing on milkweed pods as if they're having a family reunion and trying to figure out who's who during an all-you-can eat buffet. They're blood red, in sharp contrast to the green plants.
Have you seen the large milkweed bugs, Oncopeltus fasciatus, and the small milkweed bugs Lygaeus kalmii? Both belong to the seed bug family, Lygaedidae. We recently spotted small milkweed bugs on a patch of showy milkweed (species Asclepias speciosa) in Sonoma.
Milkweed bugs are primarily seed eaters, but they're opportunistic and generalists, says Hugh Dingle, emeritus professor of the UC Davis Department of Entomology and Nematology, an insect migration biologist who also researches migratory monarchs.
"They'll get protein from wherever they can find it," said Dingle, author of the popular textbook, Animal Migration: the Biology of Life on the Move. They eat not only eat seeds, but also monarch eggs and larvae and the immature stages of other butterflies, Dingle told us back in 2016. They eat other small bugs and feed on nectar as well. Some scientists have seen them feeding on insects trapped in the sticky pollen of the showy milkweed. (Read about the opportunist Small Milkweed Bug in the Journal of the New York Entomological Society.)
The bugs feed on the toxic milkweed, rendering them distasteful to predators. Their warning colors (red and black) also tell prospective predators "Leave me alone; I don't taste good. If you eat me, you'll be sorry." They sequester and store cardenolides (cardiac glycosides) from the milkweed.
In the fall, as the seed pods burst open, monarch enthusiasts scramble to collect the seeds for next year, but they usually have to compete with the red invaders.
If they're still around...